My professional experience is pretty much as yours as a family member.
The world of directness and honesty is not a good communications strategy with this group of patients.
They ususally know something is off but are not sure what it is, and interesting dilema. Trusting the caregiver is extremely important.
I concur with your statement about eating, just tell them and do not ask unless...they have reduced intake or are not eating
Then a trip to the MD to rule out medical causes, and a questiona along the lines of what did your Mom make you to eat tha tyou liked. Admittedly if it is late satge this is a wasted bit of breath, but why not...These patients seem to have many stories of old, and those stories have food chapters in them.
I've noticed in 75% of these patients like sugar, could be addicted to sugar...and if the food is Sugar based becareful how much you make for them, since their exercise is not as robust as it once has been for metabolization
I try to cut it out of the diet, but ususally this is a health pipedream. But I cut it down in my cases.
I think you've done an admirable job of outlining problems and care