All of those sound like bugs which have sneaked in during the update. I have little time to test everything (I don't use the mod myself) and people don't always report bugs they find, so I wouldn't be surprised if those are simply bugs.
Please always name your specific RM version, especially when using the faster moving snapshots/beta versions. I recall fixing something about missing hands in 1.13+, are you using the latest version (2.2.0-b1 as of writing)?
The outer skin later is a known (very low priority) issue, see this forum thread.
Yes, please do provide as much info as you can. Crash reports are best put on https://paste.replaymod.com and then linked here (the forum makes reading them quite difficult and also has a limit to post length).
The main menu looking broken is the result of both RM and the ModMenu mod trying to inject their buttons into the main menu. I've already fixed it (will be in 2.2.0-b2).
Ok, now this is weird. The previous version crashed when I tried to render a clip and it just sent me to the MC main menu. But this time it crashed the whole game if I try to render (crashes after about 2s of rendering) or by just pressing the camera path preview button.
Here's the crash report https://paste.replaymod.com/epuxutizaz
That looks like the same issue but manifesting itself at a different location (which at least means the previous one has been fixed).
Since I can still not reproduce the original issue, here's a new version fixing that particular crash, please give it a try: https://minio.johni0702.de/replaymod/replaymod-1.14.2-2.2.0-b1-13-g75c4c72.jar
Welp.. I got another random crash.. (but not as intense) 1.14.2 really messed up the mod.. I'm also encountering random crashes when I click somewhere on the timeline and it reloads the world, but its like a 1/5 of a chance that it randomly crashes, locks up. (And I don't know if it's true, but it seems like the mod doesn't like close up movement. I especially saw more crashes when I'm making small close up skits. Probably not the case, but hey what do I know 🤔)
Here's the crash, but this one is kind of rare because it happened to me just once.. https://paste.replaymod.com/igubayeges
More noticable are random locks up of the game. (It looks like it would load something up [loading screen], but it stands still and you have to reboot the game.)
Are these random crashes actual crashes (i.e. game closes) or all just lockups (i.e. game unresponsive to inputs)?
I've been able to reliably reproduce one lockup by clicking very close to the beginning of a replay (might also be at world changes, haven't tested those). Could this account for the lockups you're seeing?
Anyhow, I'll be posting a RM snapshot once I've fixed it so you can be sure.
Lockups are quite difficult to debug for end users since the game doesn't have any builtin tools to do so. If you're feeling adventures (or already have experience in that direction), you could installed something like VisualVM which will allow you to take thread dumps (snapshots of what the game is currently doing / stuck on) which can make debugging lockups a lot easier.
The other invaluable tool in debugging lockups is a reliable way to reproduce them (especially on the developers/my machine).
The crash report has me puzzled. It's quite clear on what's wrong but I've no idea how it got into that state. Do you happen to still have the logs for that session? They might help shed some more light on it.
The logs might also be helpful in the lockup case but be sure to leave the game running for at least 30 seconds before killing it and grabbing the logs (unless it's already spamming the log), that'll show if it's related to the lockup I've got here.
Here's the snapshot which fixes the lockup which I was able to reproduce: https://minio.johni0702.de/replaymod/replaymod-1.14.2-2.2.0-b2-3-gb846d53.jar
It also fixes a NPE which can happen while the world is loading (or re-load), in case you've come by one of these, and it should include the fix for Z not working during rendering.
I'm still puzzled by the crash, maybe I'll be able to get a fresh look at it tomorrow.
Thank you for all the bug reporting you've been doing, I very much appreciate it.