Question [Q] add on dictionaries for spell check

How do I add another add on dictionary to a stock rom?

Why do I want this?
I ran a rooted stock version of 4.4.2 on my Nexus 4, but completely wiped and unrooted it with Mskip's brilliant tool. This was needed in order to run Good for Enterprise, as my N4 will now act as work phone next to my new N5.
I always switch between English and Dutch keyboards and this always worked perfectly. However now it doesn't any more. I checked the differences with my N5 where it works fine. Turns out 'dutch' isn't listed any more in the add on dictionary list.

What have I tried so far?
- Every single option and option combination that could affect the keyboard or spell check
- Copying the 'LatinImeGoogle.apk' and 'LatinImeGoogle.odex' from the N5 to the N4 -> result, I have the user dictionary from my N5, but not a working spell check
- Looked into installing a fresh set of GAPPS, but haven't done so far -> any idea if this might work?

All thoughts to address this issue are welcome!
Nexus 4: work phone
Nexus 5: private phone