It is definitely a plus that you know lots of languages, but just knowing a high number of languages by itself would not generally count as a spike at highly competitive colleges. However, there are things you can do to boost your chances.
This study by the European Union shows that about 10% of Europeans speak 4 or more languages.
Allen writes about spikes in his article on spikes in college. Spikes for places like Stanford start when you get to the prestige level of, say, ranking top 100 in a large country's math competition (e.g. Germany). Germany has on the order of 4 million high school students. This means that spikes should be a 1/40,000 prestige, or at least a 1/1,000. Top 10% wouldn't come close unfortunately. The basic reason is that a lot of people from Europe know lots of languages -- you need to make that more specific.
Some things can could make this into a spike include:
- Are you very fluent in all the languages? If so see maybe if there is a competition on language fluency. If there are awards based on this it would work well.
- Can you apply your languages in a way to help people? For example, can you start some organization that empowers intra-European understanding (or International understanding even -- I see you've learned Chinese too!)
Also, depending on how good you are at tennis, piano, and guitar, those could be things you can develop into a spike (only if you're really into them and don't mind them getting a bit more competitive). Are you already top 1% in any of those? Then that may be a better starting point than languages.
Generally, to start developing a spike, you are best off starting in an area where you're already as top percentile as possible.
 http://ec.europa.eu/public_opinion/archives/ebs/ebs_386_en.pdf Printed Page 12