+1 on this.
This would be very useful for Script Filter workflows that take additional parameters after the autocomplete options are shown. For example, I'm building a workflow to add items to a list. The usage is as follows
list [filename] [some arbitrary text to add to the list]
I want the list to be able to autocomplete filenames for files in a pre-set directory, so it is necessary to use a script filter. However, after adding the file to the parameters (for example "list Groceries.txt"), I no longer need the benefits of the script filter and just want the query to be parsed when I press enter. Currently if you hit enter before the script filter has had a chance to finish processing the query, it will truncate the end of the text.