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.
The translations have been merged by calling
python development/tools/mergepo.py -n ../lyx-2.1-git/po
cd po; make update-gmo
For some languages it may make sense to merge also changed translations,
but this neds to be decided by the individual translators.
