... One minor thing that bugs be is how difficult it is to type the letter theta using the letters "t" and "h", as it usually ends up registering as "τη."

GR translit?

since the GH migration spell checker doesn't work anymore

when you write "с" and then press "x", for example "происходит", it changes it to "ш". It should not do it if you type "s"+"x", only of you type "s"+"h"

It's a major issue! Once a user on Mac tries to select the whole text in the text field it deletes irreversibly the text in the text input field! Not sure if it happens in specific or all browsers on Mac.