Alternative Search & Replace on Mac

I would like to use regular expressions to replace an entire line of uppercase characters with the same characters in “Capitalize Every Word” mode (or Title case as it is generally called.) I used to be able to use Alternative Search and Replace but the version I just downloaded is screwed up (see attachment).

C:\fakepath\Screen Shot 2020-05-12 at 6.36.07 PM.png

(edit: activated image)

No idea what could be the problem with AltSearch (and you likely need to contact its maintainer), but you could alternatively use normal F&R dialog to look for regular expression like

(?<=\b\p{Upper})\p{Upper}+\b

(do not forget to match case), Find All, and then apply lowercase to the selection using Format>Text menu.