Nothing. I always use the standard configuration from the services I've installed. If something doesn't work I go into those logs and look what's wrong.
Since nobody has suggested it, I'm adding AnySoft Keyboard to the list of alternatives. It takes some time to train custom words but after that it's actually quite nice. Even the swipe typing works quite well.
https://f-droid.org/en/packages/com.menny.android.anysoftkeyboard/
Can dou you name some? I highly doubt that you can buy data from a specific person.
You would need a lot of data and the know how to trace that data back to a specific account/user