At this point I gave up waiting for translations and I'm reading the original using my phone camera with google translator. The manhwa is already on chapter 169... I don't regret one thing, I'm enjoying like crazy.
so how long till, let's say, an explicit confession or any kind of development, reassuring that this story is a yuri romance? and not just a slice of life all girls school story?
Judging by the raws (166 chapters) the whole story is like Marimite. So many close friendships between girls, but only het couples are established in romantic way.
The last several chapters have been very clearly signalling a move to an explicitly romantic relationship between the two lead characters. The het couple is the beta couple of this series - they exist as a foil to Yukino and Nobara. Like literally they exist story wise to push the main couple together. Also as a way to make sure the readers know that Shouji is actually just close to Nobara as a relative and not a real love interest, that was just a head fake.
This series is very slow... But so was Marimite. I think this series is trying to bridge the gap between Type S and more outright yuri. The het couple is the most explicitly romantic so far but aren't you basically forgetting about Akai and Ookami-san?