I just have tested the (obsolete) Version from above plus the (more recent) Version from the German Audacuty forum (attached below) and both versions work with Audacity_1.3.13-beta on Debian Linux with no errors.
If the attached plugin below still raises errors (“Nyquist did not return audio” or similar) then in the “Subliminal” effect window press the “Debug” button instead of the “Ok” button and copy the text from the Audacity Nyquist “Debug” Window here into the forum.
subliminal.ny (1.11 KB)