The switches in the joystick are already Omron, changing it out to a TP-MA isn’t really going to do you any good from a quality perspective. Once you have the gate locked onto the joystick, the switches won’t wiggle. If they do, there may be a slight defect from the manufacturing process of the gate, which you could probably correct by adding a thin layer of felt or something between the switches and gate to add extra tensions for extra security. In my SE stick, the gate had a defect that stopped me from fully engaging down-back which I had to correct, so maybe the gate in your brawl stick isn’t quite correctly keeping the switches in place.
From what I can tell the switches in the buttons are Sanwa clones, you should be fine getting some. But honestly, they’re not that different, maybe a bit less tension on the Sanwa (for that extra mushy feeling, bleh) but the cost to get new switches and pay for shipping will probably outweigh any performance benefits you think you may get.
To be frank, when I first started playing on stick I was all about upgrading the parts because I thought stock was shit based on name and word of mouth. However over time, I’ve found that isn’t the case. In my prototype stick, I have stock Hori buttons and I’ve been playtesting that for about 6 months now. About 98% of the people here will talk big shit about stock (not the new Kuro’s from Fighting Edge) Hori’s, but they aren’t bad. They use the same exact switches that Seimitsu use in the snap-in line of buttons, so if you like Seimitsu, the Hori’s will work just as well. I’ve seen some people say the plastic isn’t as good, but the Hori’s have taken a pretty good beating, surviving a 4 foot drop while Sanwa snap-ins have broken on me in the past from simply changing them out. Point is, I’d stick out your buttons a while longer until you wear them out, and then simply buy some new brand-name ones when you need them.
I’ve tried a variety of buttons, and most are good. Except Yenox. Those are the most awful buttons I’ve ever laid fingers on.