@LoufromNH
Create a Dynamic Content Key
Instead of the Switch function I'd recommend creating a JSON object instead and using an expression. I would recommend creating a new flow for you to test out the concept first before adding it to your current flow. I demo this concept in this section of one of my tutorials.
Add a Compose action with your dynamic content key. Insert opening and closing curly brackets. Between the curly brackets enter a line for each content pair.
In your case, the location would be on the left (before the colon) and the email address(es) would be on the right. If you have multiple email addresses ensure you have a semi-colon separating each.
{
"Location 1": "email1@email.com;email2@email.com"
}
There should be a comma after each line except for the last line.

Add another Compose action to store a testing value (aka Location in your case). Tip: Always rename your actions especially if you have multiple instances of the same action in your flow. It'll help to keep things organized.
This Compose action is optional, you can insert the value right into the expression. However to help you better understand what's going on, I recommend you use a Compose action. You will replace this with dynamic content from your actual flow. Keep in mind this value must match the text exactly as you have it in your key. Enter any value for testing purposes.

Add one more Compose action to store an expression. Insert a question mark and square brackets.

In between the square brackets insert the output from the Compose action above.

Go to the start of the expression by pressing the up arrow key. Insert the output from the Compose action with the JSON object.

This expression will output the value on the depending on what value is inserted into the square brackets of the expression.

Run a test. Review the outputs. You can adjust the value in the Compose action to another value and run another test. Ensure the output is what you are expecting.

You can copy these actions int your current flow and insert the appropriate dynamic content (location value in your case) into the Compose action that is holding the value.

----
Array Variables
It's unclear to me the reason you have initialized these two variables:

When updating a multi-choice person column. The array structure that is expected is
[
{
"Claims": "emailaddress1@email.com"
},
{
"Claims": "emailaddress2@email.com"
}
]
If the Trainee's dynamic content is a multi-person field, you can use a Select action. In the From field, insert the multi-person dynamic content.
In the Key field, enter the word Claims. In the second value field insert the multi-person email dynamic content.

Run a test. This is what the output should look like.

You can take the output from the Select action and insert it into the multi-person column field of your Update Item action.

Get the Managers
The Select action outputs an array. You can use the output of the Select action in an Apply to Each action. The Compose action is optional, however it can help with troubleshooting. I'm using it to output the current email being looped through.
You'll need to insert an expression:

Insert the Get manager (V2) action.

Add an Append to Variable action to collect the display name and email address of each manager. The format is the same as the JSON object.

Add a Compose action outside of the Apply to Each action to output the variable.

Run a test. Review the outputs.


Use a Select action to collect the Email Addresses only. In the Fro field, insert the output from the Compose action above (or the variable).
Insert an expression.
item()?['Dynamic Content Key']
Replace the text in blue with the appropriate key. In this case, Email. You'll need to repeat this for the Display Name.

Insert a Compose action and use the join() function to convert the email from an array to a string.

Run a test. Review the outputs.

Scope Action
I would recommend adding Scope actions to your flow to keep it organized. The Scope action is optional however you can quickly collapse multiple actions with a single click.


Hope this helps!
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