I know Buildcraft is MIT license, but not sure where I could report this Java developer genius - https://play.google.com/store/apps/details?id=com.danielzakirbaev.BuildCraftFactoryModuleMod.MinecraftPE&hl=en

EDIT He's also found a way to port tons of over mods...

i'm not sure this is an copyright issue, i've seen different MCPE mods in the past and so far most of those seem to be written in javascript to are a complete rewrite of a mod

also considering the fact all his screenshots are from the java edition i doubt it even works and is a legit thing, have you tried it out yourself?

The old assets are generally licensed under the MMPLv1, however none of us own the relevant copyright so we can't do anything. We don't hold trademarks on the "BuildCraft" name either.

Looking into the APK, I'm not sure what it is trying to achieve, it has seemingly nothing to do with BuildCraft or MCPE, and I wouldn't touch it with a ten-foot pole.

Looks like the developer has loads of these. Took a quick look at the APK for "DecoCraft Mod for MCPE", seems to just be a bunch of adverts. Probably just trying to cash-grab.
Here it downloads a file from google drive, this appears to be a zip with the real DecoCraft in it (obviously not going to work).
Seems that the app only consists of several screens each with an InterstitialAd

There also is a mysterious Tech mod MCPE.jar file, seems to be some calculator program

You should report these to Google then. I already reported the BuildCraft one for you, since it violates their guidelines.