First off, yay for free roaming!
On pellets, too many pellets can cause obesity, I think, but different people have different opinions on use of pellets.
I personally don’t like giving my buns too many, as I supplement their diet with herbs and fresh veggies. I limit the pellets for my bunnies to 1/4 cup (1/8 cup per bunny) daily. I haven’t looked closely at all the ingredients in the pellets I use, though.
I love that you give them both hay and fresh grasses. I too use dandelion root, but dried and just a pinch about three times per week (I think too much can give them upset stomach? But I’m really not sure…). Do you give it fresh? I also like giving them dandelion greens every other week for a couple of days (my buns loooove dandelion greens and root).
I have absolutely no knowledge about the seeds you mentioned (sorry).
Those are my two cents on that. I think your buns are lucky to have such a caring care taker! 