I'll wait for you bro...
Something must've happened lol.
BB's sudden bounty boost makes no sense otherwise.
The rest of his crew members probably did something notorious, only Devon & Shot came here.
Shiryu & the rest must also been sent on missions kinda like how Burgess alone came to Dressrosa to steal the Mera Mera no Mi.
About Jimbei and Crocodile, i don't think neither the revealed strength of Jimbei nor the any upgradation in TS for Crocodile would make sense related to there revealed bounty. A grown-up or middle age man like Crocodile, how much of strength he can achieve in one TS. Same goes for Jimbei, his strength at 400M when he was also a middle age man and now won't be with that huge gap.
Either its revealed after only 2years of MF incident is related to after how long they became active again coz at FM Island, Jimbei said he has no idea what his bounty is while former was around 400M or god knows what Oda is thinking.
Jimbei being one of commander for such bounty is reasonable but even the 3rd commander of WSC is only 1B that is below Jimbei's current bounty but hey he didn't even beat down Jack.
While another reason for there bounties after 2 years could be related to revocation of Schibukai system as well along with when they become active.
Like in Boa Hancock's case without doing anything big or evil , she also got bounty revealed suddenly or like with other colleagues. But about her strength, with such bounty she should be above WCI Luffy but even with her haki (even as CoC user) she couldn't counter BB or sense him approaching to escape or again counter was quite unbelievable.
About BBPs things, hmm definitely that's quite possible. If his other crew mates wracking havoc somewhere else.