Your Romanian GC would complete all documents (school profile = very important) pertaining to 8-11 and send it to your us GC to upload because your transcript would be divided into two segments in the common app.
Graduating from a US high school means three things: 1) in some states you may be considered for in-state tuition (which is no help at all if 20k is as unaffordable as 50kfoe your family but in some cases can help) and 2) you will be considered a domestic applicant like all others in the US for “meet full need” Pomona college and it greatly increases your odds. Downside is that Pomona College is one of the most selective colleges in the US so your odds go from 3% as an international to 9% as a domestic applicant, roughly. You could apply ED if you manage to score 1480+ on the sat in June or 32+ on the act and 750+ in two subjects. And 3) if your application is strong in September you can apply through Questbridge. Imnassuming your family akes essential than 30k in yezlrly income. It means hitting the ground running right away at your high school (a week adjusting rather than a month). And obviously it’s better if you’re in an early school year start like Florida starts school before August 15) than in a late school year start like NYS (which starts school after labor day, so, three weeks later).
Unlike most exchange students who can fill their schedule with whatever they like you’ll need to take hard classes and will have graduation requirements. (Details may be better PM’'d as they may be too long and personal for a public thread).