Can activated charcoal/anything else help reduce awful smelling flatulence frequency/odour in flare?

Perhaps. UC drugs can help to get the inflammation under control, and getting into remission will eliminate odor and gas.

I've never used charcoal but 3 things I use to rebalance my gut are: red or green clay mixed in water AKA clay water, oil of oregano-couple drops in 6-8 oz. water and quality probiotics with water (I have VSL#3 on hand).

Sometimes my gut flora just gets out of whack and needs a reboot, nothing drastic and usually only take 1 or 2 doses of one of the above (NOT all three). Don't go overboard. I think older generations called it a "tonic" when they would have some dandelion or other bitters which probably do a similar function.

Don't take clay water or oregano oil near taking probiotics, probably cancelling out the good guys.

AF: I take VSL#3 before bed, no food. Maybe I read somewhere that time is outside active digestion period, dunno. I eat all day long so bedtime seems right. But in times of distress I'll mix a glass of VSL powder/water and drink it whenever, quiets my gut down fast.

Yes the best probiotics have coating or capsule that is designed to survive past your stomach acid. VSL is but one example, other less expensive probiotics have that as well.