Yes, there is Alcohol related dementia but if she has been in recovery for 30 years I doubt that is the cause. Brain shrinkage is a symptom of several kinds of dementia. So you really don't know much. My best is the prescription was for Namenda, Aricaept, or Exelon.
The compulsive obcessive behavior your Mom is showing is typical. The target of the obcessive compulsive can be different. You Mom has her coloring book. My Mom had her window washing and flower bed pine straw. Between bouts of window washing (sometimes severeal times a week) Mom would sit in the flower beds picking leaves and twigs out of the pine straw and "fluffing" it. Yes it had to be done just so.
It is only when behaviors became dangerous to your MIL's safety or mental well being do you need to worry. They are going to do bizarre things. If she gets agitated to the point of hysteria, combativeness, or become extremely depressed... then you might want to talk to her doctor about medication to relieve these unwanted emotional symptoms. But don't worry about the bizarre behavior itself.