This was discussed in the thread "Translations of Math environments in LyX
output for LyX 2.2" at http://www.mail-archive.com/lyx-docs@lists.lyx.org/msg08633.html
and has been reviewed. The problem was that in 2.1, the portuguese translation
was correct in lib/layouttranslations but different in po/pt_PT.po. In fact,
the translation is the same for all three languages spanish, portuguese and
brazilian portuguese.
These have been added by 36d7b40c, before we had always UNIX only.
poedit can read the mixed files just fine, but python polib (which is used
in po/lyx_pot.py) refuses to load files with mixed endings.