I couldn't find a way to send a simple 'bug report' directly to Adobe, so I guess I'll have to write it as a "conversation" on their forums for Photoshop.
So, I had to google on this problems for 30 mins before I could find a solution to this problem myself, but I'll describe it in a simple way: - Since most foreign keyboards don't "have" brackets (The "[" & "]" keys), it instead, for example uses the "," and "." keys instead for using changing the size of the brushes in photoshop.
Only that, after I had updated my Mac version of Photoshop, I found out that I could only 'enlarge' my brush, but not 'minimize' it. As my google-ing about keycommand options had me find out, I saw that in the settings there existed another option that prioritized the brush sizing with ",". (I believe it was something like, previous brush) So I deleted that short command and now everything is working the way I prefer it to.
Hopefully this is adressed sometime soon, for the sake of others not having to do a bunch of detective work on potential problems. 🙂