For some reason ignoring errors doesn't work for me. The new function, doesn't add a keywords field to non-standard bib entry types, it just puts the tags before the beginning of the bibtex entry, which would mess up the resulting bibtex file. 

The regexp functions I used are based on standard bibtex syntax, so they should work in all circumstances. I tested my fix under various conditions and with various variables set and it worked everywhere I tried it. 

If you are worried about licensing, you could wait  to apply the patch until I receive and sign the license, but I think that it is a sufficiently small change that it should not be an issue. 

All best,

Leonard