Need help to change ComboBox error message

I have a ComboBox that requires the user selects an item from the list (if anything else snuck in it would cause unspeakable horrors, this must be moronproof) so I set the MatchRequired property to TRUE. The problem is the rediculous error that would confuse the user as I anticipate the user will be a beginner of the most primitive kind.

How can I change the error message from "Invalid property value." to something more obvious like "Select from the list, IDIOT!" (just an example, my message will not be quite that angry)? While I'm at it, the error box's standard title of "Microsoft Forms" would be better off as something custom as well.

I am aware of changing the Style to require someone to actually pick from the list with no option of typing but this in itself is a problem as the list has 486 entries which all start with one of three values and are a combination of letters and numbers that cannot truly be put into alphabetic/numeric order and be at all simple to find.

ex: (all start with P, T or M but have random characters following)
P413MT12
P2175F34
PH12367L
T690UD0
T3D541
TG45CV
M402M43
MDF348R
M98G98L
etc...

So my only solution I think would be to find a way to change that error message (and error box title). Can it be done, and how?

Thanks in advance!