My name appears 5 times in this thread so far.

It appears there are two parts to this question.

1) Is there need for bullet trajectories to be calculated in the dedicated server?

Yes. When a client shoots, he basically sends a simple packet saying "I shot this weapon, which is powered-up/normal at this gunspot". Then the server will decide if the shot hits another player and replies appropriately. Sure, the client may see that his bullet actually hits the player, but if the server did not, then the client won't actually see that player getting hurt.

2) Can Neobeo do it?

Tough. For a start, messing with anims gives no clue to calculations of trajectories. What happens is that you need to completely re-compute it from scratch, or extract the info from the ASM, and I'd prefer the latter. Theoretically, how I would go about doing this is to intercept the ASM of a function where the server receives the shoot packet, and extract from there. This is not an impossible task, but the conversion could be a very tedious process.

With regards to the original topic of ideas for such a project, everything I can think of right now has already been mentioned here.