Good evening Hannu and welcome back!
I would love to answer your questions.
Will the created event be in one language when submitted by Community Events form? (the site default language) The site is using qTranslate language plugin. Is there a test version of plugin, which we can try before purchasing decision?
As stated previously, officially the only multi-language solution we support is WPML.
But even at that, WPML is currently not compatible with Community Events.
The good news is that we are working on compatibility of all of our add-ons with WPML. Unfortunately, I cannot commit to a release date at this point. But stay tuned!
In the meantime, there are some of our customers that had some relative success getting our plugins to work with Polylang (I am unsure if that applies to Community Events to be honest). But we have no report of this with Qtranslate.
We do not offer a test version, but we do have a 30 day refund policy (which is the second best thing).
Let me know if that helps.
Have a great day!
Geoff B.