Remove dynamically added field using button with $index

Could it be you just need an unique key set for the repeat children region?

Make sure to pick the $id from your data store and test again please.

it's impossible to make this selection, maybe because it's in the form:

Something looks broken on your page ...
Ok then simply add the key to your code like this:

<div is="dmx-repeat" id="repeat_languages" dmx-bind:repeat="ds_languages.data" key="$id">

thank you very much, it seems that this fixed those issues!