Never overload!
You've already stated the breaker is tripping because you are overloading it. NEVER do that. If you are doing something to overload a breaker, stop at once and discontinue. Every device has a data nameplate which tells you how much power it requires. You can read that nameplate and add them up.
If you can't power all that equipment in a bedroom maybe move the home office to somewhere with a surplus of power. One person we helped was in a basement home office with only one 15A circuit. In photos we noticed the service panel was in the room and had an "electrician's receptacle" on a dedicated 20A circuit. That was easy: use that!
- Replace with a breaker that is less "twitchy"?
No, we already know why it's tripping, you are overloading it. A less twitchy breaker would fail to do its job.
Never over-fuse!
Why stop at 30A? Put a 60A in there and it'll never trip LOL. "Oh noes, I would never do that, it would degrade my fire protection" well, so will putting in a 20A. The 15A is there to avoid overloading the 14 AWG wire.
The largest circuit that can have normal outlets is 20 amps which in turn requires 12 AWG wire. That is generally my advice because you can put more loads onto 20A circuits than 15A. The price isn't that different.
Expand at will
Bedrooms require AFCI breakers. Siemens is the only maker of AFCI tandem breakers.
If you want to add one or two 20A circuits, you can do that just fine. I would do that and then run two additional 20A circuits, placed so each circuit has 1 or 2 outlets in each bedroom. That gives each bedroom access to all 3 circuits. That way you don't have a situation where one 15A circuit and one 20A circuit is not enough and you really need a third, but sadly it's on the other side of the bedroom wall.