I think a very failsafe approach for checkmainscreen is adding a small tweak like this:
modify waitmainscreen to include only the check and return true if main screen, otherwise return false

waitmainscreen()
  while 1
     if detect message, click reload, wait 5 sec, exitloop
     else
        if attacked, click okay, wait 1 sec
        if things are opened, click away, wait 1 sec
        if x button, click x, wait 1 sec
        if chat, click close chat, wait 1 sec
        if victory or defeat scene, click return home, wait 5 sec
        if end battle button, click end battle, wait 5 sec
    endif
     if main screen, return true, else return false
     exitloop
  wend
--------------------------------------------------------
checkmainscreen()
  if not in main screen (the 284, 28 check)
      while not waitmainscreen()
         if 10 minutes passed relaunch BS (ensure not 6 hour break, take 2~4 minutes to get to mainscreen)
      wend
   endif
--------------------------------------------------------
It can handle 6 hour break as well and doesn't have to use _sleep, if break message appear anywhere during the process bot just run until getresource () and call checkmainscreen() again (it will loop and click reload every 5 sec)

I think we should discuss on the approach first before implementing in code, so it can be optimized more easily before actual release