Hi
We have adapted the VST3 license in order to cover the case of porting to other languages.
Check § 2 - section 4 to section 8
What are the licensing options for VST 3? - VST - Steinberg Developer Help
You will need a written agreement from Steinberg (§ 2 section 4) and the developers using these porting have sign the VST 3 Plug-In SDK Licensing Agreement (§ 2 section 7).
Cheers