I know your probably looking for a MUA's input but I have LOT of freckles... A LOT.
I use Clinique's superbalanced. It's considered "medium"coveraged, has a fantastic smooth finish. My face routine includes; washing, moisturizer, primer, BBcream, and my foundation. I rarely use concealer with this foundation.
Also, just imo with my freckles, foundations that leave a "dewy" finish usually work best. Dunno why, just seems like they do.
Full coverage foundation on freckles usually for me gives a weird mask effect ( I'm sure you've encountered which is why your asking). Depending on the brand/type you can always mix foundation with a primer or moisturizer to make it a little thinner too, and be sparse, blend it out from the point of the blemish.
I am NOT an MUA, so this is just personal experience trying to gob stuff on my face. Good luck.