Kritias in August

I wonder, why are there like 2-3 versions of each Kritias monster? (like level 185/210)

Because of the chain quest. You get access to the higher level monsters as you complete parts of it.

I thought they decided to ditch Kritikas since Hekaton would cause too many problems.

Makes no sense as getting Kritias doesnt necessarily mean that Hekaton is coming along it. EMS for example got Hekaton arround 2 months later than Kritias.