I am about to start a community project which will allow international users to create content online. There will be multiple languages but all content will remain on the same site/domain. Could I run into a SE penalty problem because of this? I'd love to hear your story if your site contains several languages
Never went into such situation.. As long as 2 or more language are not mixed up....on 1 page...it is suppose to be fine. But certainly not the best for SEO.
I have made some multilanguage sites and will certaintly recommend: - Make sure all url's are unique for each language. You can ofc set the language by sessions or cookies, but be sure to differ the url's - describe the language in your meta tags and follow all other general seo guideliness and you are all set. Got no problem with any SE and have a full indexing of all languages. Good luck