when you morph into a creature such as a bat or guardian or spider, the game automatically starts walking you (or moving you) in a random direction. when a cow from animania, your screen starts spazzing because the game pushes you super fast into the closest block. I do not have more player models installed, and the issues go away when in player model.

See issue #190, I think that's what you're talking about (at least about shifting). The issue is very likely to be Tropicraft mod. The screen shaking on the other hand, might come from another mod. If by unistalling or disabling the swimming animation doesn't fix screen shaking issue, then it must be another mod (of which I'm unaware).

Sadly, you failed to take a look at the linked issue... here is a quote from the linked issue 😞

Please update to the latest version of Tropicraft and disable the swim animation in the Tropicraft config.

No problem, happens all the time, I got used to it. I'm 99% sure it will fix your issue. 😂