@AkkiDa My CAG grazes all day, I would never withhold food. And frankly, soaked pellets sounds gross to me. If my CAG absolutely refused pelleted food -- I'd just let him win that battle.
@tikobird256 Mine is an overall good eater -- but after 24 years it makes sense that he's 'accidentally' tried most foods and eventually decided they weren't the devil's poison. Mine readily accepts fresh fruit/veg, cooked rice&pasta, some nuts -- plus mine eats some of my dinner (as well as eating seed and pellets). But when I got him, he'd eaten mostly seed (but he did already like fruit).
I say keep offering him things. And I don't mix/hide foods -- mine likes to carefully select and examine each morsel he eats. So you probably won't fool yours by 'mixing' or 'hiding' it in with other foods. My experience, anyway.
As far as waste, I dump all his dishes outside and the outdoor birdies/squirrels eat what mine 'didn't eat'. "Didn't eat" doesn't mean rejected, I just put too much in his dishes.