It is normal for the converter to stop working when there's been a major EU4 patch without a matching CK2 patch (yet). This is because the new launcher is looking in the wrong place for CK2 exported files.
What you could try is reverting EU4 to 1.28.3 , then import the CK2 mod there. Once in and saved update to 1.29.2 again, see how that goes.
Hopefully the next CK2 patch will fix this.
Or Copy the Mod (converted CK2 game) from \Documents\Paradox Interactive\Crusader Kings II\eu4_export\mod to \Documents\Paradox Interactive\Europa Universalis IV\mod
All the best!