Hm. Normally EU keeps both branches - Stable and Development - updated in parallel. In any case, for this phone (RMNote4X) it's still several months tilll planned stable MIUI 10 Release.
This is the first time that after the stable China update - the EU stable is not ready within 1-2 weeks. :-(
If it takes longer - we'd like to at least to know when is it planned.