I assume that these are Title fields.

It's not clear what to do with the &s. Do you only want an & before the last artist? ... or do you want to preserve existing &s?

eg. text Feat. John & Bob (Feat. Bill)

should the result be:

text (Feat. John & Bob & Bill)

or

text (Feat. John, Bob & Bill)

or

text (Feat. John & Bob, Bill)

Okay I may be missing something. I've done a run on your three examples. I get slightly different results.

Let me know if what I have is okay ... or where I went wrong:

Test 1: Hitkidd Feat. Lola Brooke Feat. Gloss Up-Shabooya (Remix) (Intro (Clean) (Feat. Slimeroni & Aleza) (Feat. K Carbon)
Results: Hitkidd-Shabooya Feat. Lola Brooke, Gloss Up, Slimeroni, Aleza & K Carbon (Remix) (Intro (Clean)

Test 2: Major Lazer Feat. Major League DJz-Ke Shy (Intro (Clean)) (Feat. Yumbs & Tyla) (Feat. Ludadeejay)
Results: Major Lazer-Ke Shy Feat. Major League DJz, Yumbs, Tyla & Ludadeejay (Intro (Clean))

Test 3: Larry June-Palisades, Ca (Intro (Dirty) (Feat. Big Sean) (Feat. The Alchemist)
Results: Larry June-Palisades, Ca (Intro (Dirty) (Feat. Big Sean & The Alchemist)

Great. Download: https://2manyrobots.com/actions/DJunpridictabull---Featuring.zip

The action is called: DJunpridictabull - Featuring. You can rename it in the Action Manager.

If you run it with no loaded files, my test results are displayed, otherwise it works on selected files . After running the action, the file selection will contain only those files where the Title field has been changed.