1) Somewhere you've developed a habit of throwing scalpels in every situation. Please stop.
The thing about playing team Val/Bella is that you're going to have to get comfortable in pressure situations. Once you block, you don't have a button to get them off you aside from pushblocking. You don't have a safe DHC unless if you have 3 meters, and that's if the opponent is on the ground and isn't smart enough(or lucky enough to have meter) to alpha counter Bella's lvl3. On the plus side, successful reversal EKG > DHC Dynamo > H bypass assist + f.hp is a guaranteed combo anywhere.
2.) Counter calling. Instead of punishing Majin's LnL assist calls with scalpels, just call your own LnL assist. Every time you see an opponent call a dp assist or LnL, just call LnL. The beauty of counter calling with LnL is that between two LnL assists, the one that was called last will always win (given that the point characters don't do anything to punish the assists). The LnL assist that was called last will armor through the hit and only receive a percentage of the damage, but the other LnL assist will eat a counterhit's worth of damage. Mind you, H LnL does 1400 damage. On counterhit that's 2100 damage. Now if you add on the bonus damage earned on assists, that's a total of 2835 damage from one hit. And if it's a 2v3, then that's even MORE pain (2835 x 1.3 = 3685, but not able to test that right now). If they don't learn from all the counter calls and keep using their assist, then that assist will die.
3.) Cerebella has great air buttons (j.mp, j.hk, j.lk j.hp, throw) that all have different purposes and cover different angles, but a lot of her power and resources is on the ground. Jumping isn't a bad thing with Bella, but you need to develop a ground game. H bypass assist + f.hp lets Bella convert off of a half-screen punch. If they block both hits and try to punish the Val assist, they are still in range for another f.hp.
4.) You still haven't mastered a combo 100%. Or at least I haven't seen a full series that maxes out undizzy and ends in a super. What I think I'm seeing is that you have built up some degree of muscle memory for a combo, but you've been switching up your bnb several times to things you think are cool. I haven't seen evidence of you building up a foundation of a combo that you can do 100% without having to think about it much. There was once a time where a friend asked me to do Val's corner combo without looking at the screen. I did it, and then my friend was scared to even touch the game. But the point is, that's where you kinda want to be with your combos. Once you reach the point where you don't have to think about your combos, then you can spend the time during your combo thinking about what your reset options are and if your opponent blocked those options before. If the opponent did block it, how can you mix it up? Or if always keep mixing it up, will the other guy second guess themselves if you do the same mixup again?