I have a 1 year old Tonkinese cat. When she was younger she was known for her toxic flatulence (I swear that she knocked out a golden retriever with her farts).
But after changing her food to Fussy Cat grainfree dry biscuits along with Fussy Cat raw beef mince the farts have disappeared.
The smelly poops may be from her gut not liking the food, I would suggest getting small bags in a few different reputable brands and see what she goes for and try giving a quality pet raw meat as a soft food replacement.
As for the litter it may be too fine for it to cover up everything to her liking, I have used clay litter for years with several cats without issue.
And lastly the tray may not allow enough digging room to cover things. I have used trays with removable raised lips like this one with good results. If you are wanting it enclosed you can get furniture that holds the tray and accessories out of sight but easily accessible for cleaning.
Have you checked when the last time the extension was updated?
YouTube has gone through a lot of back end changes to try and force people to watch more advertising than videos so it could be that YT has broken the system the extension was using.
Using the broom as a grass substitute I am guessing.