If you'd prefer a swipe typing library under a truly open license, NLnet is funding [1] the creation of one by the HeliBoard [2] devs.
HeliBoard currently uses a proprietary library extracted from GBoard, which you need to add manually (since the app has no Internet connectivity out of principle), but they're asking for swipe data contributions, to be then distributed under CC-BY-SA 4.0, which'll be then utilized by their own open swipe library.
Check our more details here [3], [4] if you'd like to contribute.
[1] https://nlnet.nl/project/GestureTyping/
[2] https://github.com/HeliBorg/HeliBoard
[3] https://github.com/HeliBorg/HeliBoard/wiki/Tutorial:-How-to-...
I have contributed to this. Heliboard also great because it supports two finger swipe which is huge ergonomic improvement