It certainly would be nice if the last thing you tried worked. Though, I am not surprised that it will still require code improvement. Probably you are the first to test it.
If you want to go directly from the .speclib file, you will need to use either File > Import > Peptide Search and "build" a (BiblioSpec - .blib) library from the .speclib file, or use Peptide Settings - Library tab and click the "Build" button to build a library. Skyline does not recognize the .speclib format natively as a spectral library, as it does with .clib, .elib, .sptxt, .msp, .hlf formats. Note that these are specific formats, and it is not surprising that changing the file extension from .speclib to .clib works poorly. You are essentially lying to Skyline about the contents of the file.
Hope this helps. Thanks for posting your feedback to the Skyline support board.