Struggling with Regular Expressions

I have been using mp3Tag for years, but I have only just begun using regular expressions, and I am really having problems with them.

I tag my titles in sentence form, which gets complicated when dealing with remixes. Up until now, my solution has always been to add a "Replace" line for each new remixer I come across, meaning my regular action group includes well over 100 lines. I finally discovered REs and this forum a few days ago, and was thrilled when I found a thread with the exact RE I was looking for:

Action type: Replace with regular expression
Field: TITLE
Regular expression: ^(.*?)((|$)
Replace matches with: $caps3($1)$2

It is perfect, except for one small problem: It doesn't work. At least not for me, it doesn't. The first word after the opening parenthesis remains lowercase, and I don't understand how any of this works well enough to fix it.

Also, is there a way to restrict this change to that it only adds caps to remix information? I haven't gotten far enough with this to see for sure, but I suspect that as is, this RE, should it come across it, would give you something like:

Sweet dreams (are Made Of This) (eric Prydz Mix), or
Get low (dirty Version)

Can I get it to limit the case change to only strings containing words like mix, remix, edit, dub, etc.? I have not updated since version 2.46 out of fear of losing the action group information I've spent compiling (I'm sure there's a way to move an existing action group to a newer build, but I don't know how, and I'd be too afraid of losing everything even if I did know). This seems to be a much, much better way to go, but at the moment, it is adding as many problems as it is solving.

Possibly. I assume you also mean within parenthesis, correct? Can we make any other assumptions about those words? For instance, would the word also be the last word within the parenthesis?

You don't have to worry about that. All of your program settings and action groups are preserved when you update Mp3tag.