Reading English is just flowing water to me. The information just snarfs up.
Reading Modern Greek, I’m hyper-aware of stylistic differences; every concession to Ancient Greek or opening up to dialect was a political act up until the 70s, and I learned my Greek in the aftermath of that. Journalistic rigid syntax dismays me; I can rejoice with good choice of words, to the point of forgetting what the prose is talking about. That can happen in English, but the threshold is far higher.
Reading Ancient Greek, which I’m really not comfortable with, is assembling a puzzle. With a sledgehammer. I know what the bits mean, although there’s a fair bit of running to the dictionary; I find it very hard to put the bits together.
Reading French, and reading German, is glimpsing a coastline through a fog. My understanding is foggy, but good enough that I can skim—especially if it’s scholarly writing, where the vocabulary is more familiar.
Reading Esperanto is surprisingly smooth; there’s less texture and shoals to get in the way. My eyebrow still arches if I see a stylistic choice I don’t like.