Recently I've been browsing the French subforum of BitcoinTalk - I'm a Canadian who frequently visits Quebec every once in a while - as such my French is rusty but I can understand the basic premise of what's being discussed.
It depends on local board mod. If he is strict and if it is difficult to understand what you are trying to say, he may delete it as a spam unless you create a separate topic dedicated to your desire to learn that language.
I tried to do this with the Chinese language. I had a transaction that required me to travel there and I started to learn some words, but I did not find active members here, so it may be good for those who have the ability to write and understand sentences, but the wording remains weak, but it is understandable.