You say they are global, but then say 50 messages per 30seconds in a channel is overkill. I find that confusing. Global makes me think that I can only send 50 per 30 seconds total, i.e. 10 in channel a, 10 in channel b, and so on.
If it were 50/30 in a single channel I would agree that’s overkill, and with the limit I have placed on my bot it would never reach it. (short of an unforseen bug in the code.)
Could you clarify which you meant?