CDK : why does CDK not able to understand codepieline variable syntax at runtime?

I am trying to achieve a very simple thing Try to defined variables syntax for codepipeline manual approval action.

The variable value is coming from the previous stage which is being exported successfully.

cdk context

  "namespace": "nameSpaceValue",
    "variable1": "variableValue1",

cdk code where I am using context values

 const manualApprovalAction = new codepipeline_actions.ManualApprovalAction({
      actionName: "Approve",
      notificationTopic: manualApprovalNotificationTopic,
      additionalInformation: '#{' + props.namespace + '.' + props.variableValue1 + '}',

    });

Error I recieve

Valid format for a pipeline execution variable reference is a namespace and a key separated by a period (.). The following pipeline execution variables are referencing a namespace that does not exist.

In my opinion, I think cdk is not able to understand #{} characters at runtime.

If I directly add these values in cdk context it works.

Another way you can provide the variables from the CDK context is by obtaining the values via this.node.tryGetContext as described here:

// cdk.json
{
  "app": "npx ts-node --prefer-ts-exts ...",
  "context": {
   "namespace": "nameSpaceValue",
   "variable1": "variableValue1"
 }
}

And now in the CDK code itself:

// stack declaration code...
const namespace = this.node.tryGetContext('namespace');
const variable1 = this.node.tryGetContext('variable1');

...

const manualApprovalAction = new codepipeline_actions.ManualApprovalAction({
      actionName: "Approve",
      notificationTopic: manualApprovalNotificationTopic,
      additionalInformation: `#{${namespace}.${variable1}}`,
    });

If you also have different environments you can separate them out per environment in the cdk.json file as such:

// cdk.json
{
  "app": "npx ts-node --prefer-ts-exts ...",
  "context": {
  "test": {
     "namespace": "test-space-value",
     "variable1": "test-value"
  },
  "acc": {
     "namespace": "acc-space-value",
     "variable1": "acc-value"
  },
  "prod": {
     "namespace": "prod-space-value",
     "variable1": "prod-value"
  },
 }
}

And in the CDK code itself you can retrieve the entire environment context

// stack declaration code...
const envVariables = this.node.tryGetContext('test');
const { namespace, variable1 } = envVariables;