Words set to “No Language” do not get checked by the spell checker.
You can do a search for “UE Series” and then apply the “No Language” in the Advanced Character formats.
Something like GREP FIND of
UE(?= Series)
That would find all instances of UE followed by “Series” – but it won't include Series in the search, so SERIES would still be spell checked when you are performing that task, but it should skip UE becuase it is set to “No Language”
But that means having to do it for all instances if you type it in.
You can set up a GREP STYLE within your Paragraph Style for this.
Create a Character Style for “No Language”
Then in the Paragraph Style go to GREP STYLE and input
Character Style= No Language
UE(?= Series)
But you'd need to set this up for every word that you come across in the Spell Check that you don't want it to find.
I'm not sure if it's possible to “Script” this – where it can pluck out the Ignored Words from the user dictionary and then apply the No Language to these and remove them from the Ignored Words list (so you don't inadvertently type UE instead of say “un”)
But setting the text to No Language for certain words would definitely exclude it from the Spell Check.