We haven't changed the encoder for a long, long time so even if you downgrade I assume it will work identically. Did you get Windows 8 N or one of the variants without media features? If so, it'll be missing the ability to encode AAC. You'll have to find your own encoder in that case, encode the .wavs yourself, then just import the .m4a files in to Construct 2.
i have windows 10 Pro N and im getting this errors when importing a wav file:
w7aacenc.exe - System error MFPlat.DLL was not found
w7aacenc.exe - System error MF.DLL was not found
converted to OGG, bug failed to convert to AAC.
i have to use external converters to fix the issue?