Man they are really bad at communicating then.

You say "...the website doesn't mention these benefits at the time of seat purchase..." - does it mention it after booking the emergency seat? (For example when I click on "Boarding Pass" (tarjeta de embarque) under my bookings, it gives an overview over all included luggage - is it added there?)

My fear is that if the luggage allowance is not actually technically ADDED to my booking in the system, but merely an administrative procedure (as in gate agents are just instructed to let exit row passengers bring a carry-on), then there might likely be misinformed gate agents (wouldnt be surprising with LATAMs unclear communication) who are not aware of this and will charge me the $35 penalty to bring my carry-on on board.