Achievement with the 5th stem cell (Dead Cells)

I, being on 4 bc, wanted to install a mod on x500 souls to make it easier to grind to open suits. As a result, I accidentally passed the giant and got the fifth stem cell, but they didn’t give me the achievement (this is how it should be). But since I already have the fifth stem cell, how can I get the achievement? Or will I have to make a new save? (achievement about getting the fifth cell)