Modification of Metadata recipe "Put series into the title, using either initials .."

[Riva3000]

I am trying to modify this Metadata 'recipe':
https://www.mobileread.com/forums/sho...d.php?t=118563
"Metadata: Put series into the title, using either initials or a shortened form. Strip leading articles from the series name" ..

I wanted to modify the RegExp in Template that generates 'initials' form of Series field, so it also adds any uppercase letters into initials.

That would correctly solve series names like "MechWarrior".

I tried (also as my exercise in RegEx) but I'm not good enough to solve it, so I'll be glad if anybody can help.

Additionaly: To make it more complicated, I have books and series that contain national characters (aka non-Ascii chars aka diacritis) so it would be great if the regex would take all uppercase Unicode characters, not just [A-Z].
I understand that it might not even be possible under Python flavor of RegEx. (Just thinking complexly )