First I tried it to de-apk and repack with the apktool, after I signed it myself but this absolut not neccessary.
The APK-file ist just a zipfile, I can easily remove files in the apk and repack, the apk will still work. No absolut need to resign even.
I associated this smaller Oppo with Nuance wordlist account and like you previously said, after a while (maybe half hour) all my words came in
But till yet, there was no sync between the wordlists from two of my phones, both with Oppo 1.7.6, never mind.