Hello Leda!
It took me a bit to read through this, but I think I have a better understanding now.
I'm truly sorry this is happening, but hopefully I can help you a bit. If I can't, I am hoping someone else here can.
Since you have PlayOnMac, I do know it's a bit iffy with certain exe's and anything having to do with FH, as it struggles with running certain things from windows or installing things correctly.
One of the many issues that could be occuring with the white-screen and lag, and overall crashing could be:
1. Your subsystem that renders the game could be a huge issue.
2. The influx of members now coming into the game could be causing sudden lag.
3. Your game settings, which includes water reflection and viewing distance could affect the game performance.
I know someone wrote a guide
here and question 4 deals with crashing and whatnot.
If you need to go back to the old FH,
here is a link to do so! This is the previous update, and you'll be able to play I believe, you just won't have the new or updated maps on it. However, I do think you should try the regular Mac setup, which someone created here:
Link Here and see if it works! It may work better for you then, I just recommend trying it out if you haven't already.
If none of that works, you can always try using Bloo's download for the newest patch, which is a direct download rather than having the installer do it. Here is the direct download, if you choose to do so.
Link HereAnd FINALLY, if that doesn't work for you or you choose not to do so, you can simply use the link to the 1.15 download I gave and stick with it. Just remember to save all your files and then copy them in where they should be. <3 Hope this helps.