I tried to connect compuercraft wired modem to logic port of fusion/fission reactor, but modern us not recognizing computer interface (on 1.12 everything works ok with open computers and Computer craft) from computer craft.
Is it a bug or this feature was disabled?

Version:
Forge:latest for 1.16.3
Mekanism:latest for 1.16.3

Computercraft features are not implemented yet.
see #6445

Only for 1.16?

If you mean will 1.15 end up getting support with CC the answer is no.