The completer shows all choices independently of what was typed, this isn't the default, it is due to https://github.com/metabrainz/picard/blob/d27b419bd6f504ddb3b8761a819303b6356310d3/picard/ui/widgets/scripttextedit.py#L178 which sets `QCompleter.CompletionMode.UnfilteredPopupCompletion` for the completer popup.

I suggest to use normal mode instead to limit the number of choices to what's actually entered, for example if user enters `$a` I expect it to show `$add` and `$and`.