Byak is not an old engine at all. Besides, it's in early development phase. Only the source code is available and no compile is provided yet according to its homepage at github.
Usually Jim Ablett does't skip any engine source code. Thus, he didn't wait long to compile it for Android. It makes now more than 140 engines available. At least 100 are compatible with tournaments under Chess for Android 5.0.5.
Byak, in its current stage should not be strong yet but it deserves a try for sure. In case it passes my tests, it will become a part of Rapidroid, in order to save the whole world from the unbearable headache caused by its unknown ELO.
Download and enjoy Byak: HERE