I have custom input handler under construction to prevent flooding dictionaries with words from other languages.

Dictionaries are based on commercial and closed source xt9 and adding custom dictionaries into that is not possible. I would be very much interested to implement custom word prediction and dictionary solution based on presage. Presage could be even used as plugin in maliit but Jolla is holding modifications they have made to maliit source code. There is also a challenge that it should be recompiled and stock maliit installation replaced with custom one, which in my opinion is not feasible solution for larger audience.

Presage could be used as Qt plugin with QML import if anyone with enough knowledge could help in such implementation. Implementing such goes way too much beyond my skills.