I recently installed 2.0 beta and decided to connect uplay account. Sadly some games like assassin creed origins show that game has achievements but cannot read the ones i unlocked before. On some games like steep achievements are not recognized at all even though game supports them.

if you noticed it says, when you are integrating uplay, that achievements are so far not supported on uplay

so i think that feature will come in the near future.

They are not actually called achievements of Uplay but rather "Trophies" and "Challenges"
So i do not know how that will work.

same like on ps4, gog calls it achievements even tho its trophies

No, there're achievements on uPlay and they're named liked that. They give nothing but inner satisfaction by unlocking them.

There're also Challenges - they're a separate entity and give you XP for profile level and uPoints that can be used on getting rewards or 20% discount when buying games.

So far, Galaxy 2.0 only imports Challenges (not actual achievements) and it shows them as locked even if you unlocked them on uPlay.