With regards to syringe accuracy I haven't noticed anything out of ordinary except two cases:
It can be difficult to hit with syringe when trying to revive without teamkill, which is a new mechanic. I don't have any examples for this since it's has been some time since I last played on main TM server, but its pretty common and I don't know if it's intended or not. The hitbox seems rather small, and it seems like you can't revive while moving? not really sure.
Enemy player corpse, gibbed or not is blocking the revive hitbox. You can still find an angle that will work so it's not guaranteed that someone will come to this conclusion in the middle of action. I think especially when corpses don't need to overlap each other perfectly. I had a clear case of this yesterday in which I got laughed at :d https://streamable.com/b5vckh. This issue is reported though https://github.com/etlegacy/etlegacy/issues/1418
I didn't see anyone here mention neither of these situations, so maybe there is a chance that some of the complains about syringe accuracy are related? Or maybe everyone knows about it and just omitted it knowingly just like I did since I joined the forum.