Any coin will tone with heat, but that is not something I would do on a valuable buffalo as the toning pattern is very unpredictable due to the way those planchets were mixed.
AT can also be achieved with sulfer, but I wouldn't really do that either.
Unless the cleaning is absurd looking, it's probably best to leave it alone. You have a cleaned coin now. At best what you will end up with is a cleaned coin with AT. At worst is a coin that can be better described as messed up at its end result.
Are you sure it hasn't been polished. Especially since you mentioned as only having had the obverse worked on, it might just be polished. I only rarely come across a cleaned buffalo in the traditional sense. Collectors rarely cleaned those coins, but everyone and their mother was polishing them for non-numismatic purposes back in the day.
I hope you didn't overpay as a one-sided polished buffalo will lose a large amount of its value. At least it's a key date in what is probably XF, tough to find.