Arushi: Thanks for the tip about the Vestibular Rehab. I like the sound of your setup. I don't think they have anything that fancy here, but I will now know what to press them about.
Anytime!
Regarding Yoga, you don't have to know one little bit of the language, postures, etc. Start in a beginners class, make sure they know you have/had tumor and have balance issues.
I find it difficult to perform yoga in dim light (like most studios around here use) and/or some have carpeting (along with yoga mat on top of that makes for soft surface) more challenging here too. If the studio uses dim light ask that you be placed at the nearest light source or maybe they will turn up the light for you.
If I were teaching a class to you I would put you in bright light, hard floor and not expect you to "learn" to balance in these challenging situations as you are to relax in the posture at the same time holding strong and if you are fighting to keep your balance this can create too much stress.
Hope you find Yoga can help you if not for balance of the bones and muscles then balance of the mind/spirit!