Actually, they kind of do look like green cheeks to me!
They're missing the coloration for black caps and fiery shouldered conures.
I don't see the black cap faces or the green colored tail.
I don't see the horn colored beak of a fiery shouldered, nor the darker maroon tail.
I would say that they are indeed green cheeks, possibly green cheek hybrids. There are some strains of green cheeks that have the red shoulders now, as well as the opaline mutation having a higher chance of having those red shoulders. If the website was still up, I could share pictures of that group of birds more easily.
@Darklotus555 do you have any more pictures of these birds?