Concatenate values from a repeat into a single variable

In a form I have a repeat that outputs several results (they happen to be single sentences) from a serverConnect Server Action. Typically there could be anything from 3 to 12 sentences.
My aim is to put these sentences into a Medium Editor Textarea so they can be edited by the user and uploaded to a single database field.

The only way I can think of doing this is to add a variable before the repeat. Then inside the repeat put a {{var_comment.setValue(commpara_text)}} BUT I only get one of the paras in the variable. How can I concatenate the sentences?

In other languages I have used things like += “concatenate to the existing value” and not to overwrite.

This variable can then be used in the Medium Editor Textarea using something like
dmx-bind:value="var_comment.value"

Maybe I am overthinking this but I just can’t get anything to work, please help.

This needs to be client side as the result of the repeat is determined by user selection in the form.
I am working in SPAs