IMHO, no. Although this is an international board, the accepted norm has been english on this board for many years.
If it were in OMNI, it'd be one thing, but I think in the travel related fora, english should be the language used.
Some other posts (dating back a while):
The norm is that all signatures must be in english as well -
http://www.flyertalk.com/forum/11281810-post1.html (bullet point #4)