diff --git a/modules/cis-log-alerts/main.tf b/modules/cis-log-alerts/main.tf
index 340ef8834..17432b37a 100644
--- a/modules/cis-log-alerts/main.tf
+++ b/modules/cis-log-alerts/main.tf
@@ -39,11 +39,11 @@ resource "google_monitoring_alert_policy" "alert_policy" {
   project  = var.project
 
   # notification_channels = var.notification_channels
-  notification_channels = [google_monitoring_notification_channel.email.name]
+  notification_channels = concat([google_monitoring_notification_channel.email.name], var.notification_channels)
   display_name          = each.key
   combiner              = var.combiner
   conditions {
-    display_name = "each.key"
+    display_name = each.key
     condition_threshold {
       filter     = each.value
       duration   = var.duration
diff --git a/modules/cis-log-alerts/variables.tf b/modules/cis-log-alerts/variables.tf
index 01a310127..fadc34de0 100644
--- a/modules/cis-log-alerts/variables.tf
+++ b/modules/cis-log-alerts/variables.tf
@@ -39,6 +39,12 @@ variable "duration" {
   type        = string
 }
 
+variable "notification_channels" {
+  description = "Additional notification channels for alert policies."
+  type        = list(string)
+  default     = []
+}
+
 variable "per_series_aligner" {
   description = "Per series aligner."
   type        = string
diff --git a/modules/cis-log-metrics/main.tf b/modules/cis-log-metrics/main.tf
index 1b9dd31a8..fae82b01b 100644
--- a/modules/cis-log-metrics/main.tf
+++ b/modules/cis-log-metrics/main.tf
@@ -16,11 +16,11 @@ locals {
   log_filter = {
     project-owner-log = <<EOH
     (protoPayload.serviceName="cloudresourcemanager.googleapis.com") 
-    AND (ProjectOwnership OR projectOwnerInvitee) 
+    AND ((ProjectOwnership OR projectOwnerInvitee) 
     OR (protoPayload.serviceData.policyDelta.bindingDeltas.action="REMOVE" 
     AND protoPayload.serviceData.policyDelta.bindingDeltas.role="roles/owner") 
     OR (protoPayload.serviceData.policyDelta.bindingDeltas.action="ADD" 
-    AND protoPayload.serviceData.policyDelta.bindingDeltas.role="roles/owner")
+    AND protoPayload.serviceData.policyDelta.bindingDeltas.role="roles/owner"))
     EOH
 
     audit-config-change = <<EOH
diff --git a/modules/intrusion-detection-system/main.tf b/modules/intrusion-detection-system/main.tf
index 65a6008c5..61ec1b064 100644
--- a/modules/intrusion-detection-system/main.tf
+++ b/modules/intrusion-detection-system/main.tf
@@ -32,7 +32,7 @@ resource "google_compute_global_address" "ids_private_ip" {
 
 # Create Private Connection: ####
 resource "google_service_networking_connection" "private_vpc_connection" {
-  count = var.create_service_networking_connection ? 0 : 1
+  count = var.create_service_networking_connection ? 1 : 0
 
   network                 = data.google_compute_network.vpc_network.id
   service                 = "servicenetworking.googleapis.com"
diff --git a/modules/organization-se/iam.tf b/modules/organization-se/iam.tf
index 607a54f0a..057d15150 100644
--- a/modules/organization-se/iam.tf
+++ b/modules/organization-se/iam.tf
@@ -52,17 +52,17 @@ locals {
     )
   }
   iam_bindings_additive = merge(
-    var.iam_bindings_additive,
-    [
+    merge([
       for principal, roles in var.iam_by_principals_additive : {
         for role in roles :
-        "iam-bpa:${principal}-${role}" => {
+        "iam-bpa:${principal}//${role}" => {
           member    = principal
           role      = role
           condition = null
         }
       }
-    ]...
+    ]...),
+    var.iam_bindings_additive
   )
 }
 
diff --git a/modules/organization-se/variables.tf b/modules/organization-se/variables.tf
index 0ef099644..a3c7ecc55 100644
--- a/modules/organization-se/variables.tf
+++ b/modules/organization-se/variables.tf
@@ -97,7 +97,7 @@ variable "organization_id" {
   description = "Organization id in organizations/nnnnnn format."
   type        = string
   validation {
-    condition     = can(regex("^organizations/[0-9]+", var.organization_id))
+    condition     = can(regex("^organizations/[0-9]+$", var.organization_id))
     error_message = "The organization_id must in the form organizations/nnn."
   }
 }
diff --git a/modules/spanner-instance-se/iam.tf b/modules/spanner-instance-se/iam.tf
index 582d2bb14..af3e44cf1 100644
--- a/modules/spanner-instance-se/iam.tf
+++ b/modules/spanner-instance-se/iam.tf
@@ -45,6 +45,14 @@ resource "google_spanner_instance_iam_binding" "bindings" {
   instance = local.spanner_instance.id
   role     = each.value.role
   members  = each.value.members
+  dynamic "condition" {
+    for_each = try(each.value.condition, null) == null ? [] : [""]
+    content {
+      expression  = each.value.condition.expression
+      title       = each.value.condition.title
+      description = each.value.condition.description
+    }
+  }
 }
 
 resource "google_spanner_instance_iam_member" "bindings" {
diff --git a/modules/spanner-instance-se/variables.tf b/modules/spanner-instance-se/variables.tf
index d2a80a784..97f00c935 100644
--- a/modules/spanner-instance-se/variables.tf
+++ b/modules/spanner-instance-se/variables.tf
@@ -81,6 +81,11 @@ variable "iam_bindings" {
   type = map(object({
     members = list(string)
     role    = string
+    condition = optional(object({
+      expression  = string
+      title       = string
+      description = optional(string)
+    }))
   }))
   nullable = false
   default  = {}
diff --git a/tests/tools/test_blueprint_and_module_validations.py b/tests/tools/test_blueprint_and_module_validations.py
index d7da966ae..9c25e2512 100644
--- a/tests/tools/test_blueprint_and_module_validations.py
+++ b/tests/tools/test_blueprint_and_module_validations.py
@@ -55,5 +55,33 @@ def test_modules_enforce_30_char_id_preconditions(self):
     )
 
 
+
+  def test_custom_stellar_engine_modules_validations(self):
+    """Verify hardening and logic fixes across custom Stellar Engine modules."""
+    alerts_main = (REPO_ROOT / "modules/cis-log-alerts/main.tf").read_text(encoding="utf-8")
+    self.assertIn("concat([google_monitoring_notification_channel.email.name], var.notification_channels)", alerts_main)
+    self.assertIn("display_name = each.key", alerts_main)
+    self.assertNotIn('display_name = "each.key"', alerts_main)
+
+    alerts_vars = (REPO_ROOT / "modules/cis-log-alerts/variables.tf").read_text(encoding="utf-8")
+    self.assertIn('variable "notification_channels"', alerts_vars)
+
+    metrics_main = (REPO_ROOT / "modules/cis-log-metrics/main.tf").read_text(encoding="utf-8")
+    self.assertIn("AND ((ProjectOwnership OR projectOwnerInvitee)", metrics_main)
+
+    ids_main = (REPO_ROOT / "modules/intrusion-detection-system/main.tf").read_text(encoding="utf-8")
+    self.assertIn("count = var.create_service_networking_connection ? 1 : 0", ids_main)
+
+    org_se_iam = (REPO_ROOT / "modules/organization-se/iam.tf").read_text(encoding="utf-8")
+    self.assertIn('"iam-bpa:${principal}//${role}"', org_se_iam)
+    org_se_vars = (REPO_ROOT / "modules/organization-se/variables.tf").read_text(encoding="utf-8")
+    self.assertIn('can(regex("^organizations/[0-9]+$", var.organization_id))', org_se_vars)
+
+    spanner_se_iam = (REPO_ROOT / "modules/spanner-instance-se/iam.tf").read_text(encoding="utf-8")
+    self.assertIn('dynamic "condition"', spanner_se_iam)
+    spanner_se_vars = (REPO_ROOT / "modules/spanner-instance-se/variables.tf").read_text(encoding="utf-8")
+    self.assertIn("condition = optional(object({", spanner_se_vars)
+
+
 if __name__ == "__main__":
   unittest.main()