-Create a UI5 Dialog with a multivalue composite field.
-Make the fields use i18n
-Set the multivalue field to have DelegatingMultiValueFieldTransformer
-The composite field to NoOpCompositeTransformer
( i dont think the transformer type matters, it happens with all of them for multivalue)
-Open the dialog
-Fill in the fields with some values.
-Close the dialog
-Re-open the dialog

you will see the fields of the current language selected with the values inputted in them, but then you also see blank fields of the other languages as well.

So lets say you put one entry for EN, and 2 entries for DE, reopen the dialog, select English... You will see the 1 entry for EN, and two empty entries (these would be the DE ones). Then the opposite happens as well. If you select German, you will see the two entries, but you will also see one empty entry (the one from EN).

Workaround would be to use the old pages app