Hello,

The main problem of this is if someone registers in one language, it is not combined with the other 2 language's forms, so if I have 10 tickets, I actually offer 30!
Another problem is if I have the same event on several single dates, how can I set different numbers of tickets for different dates?

Unfortunately, with Joomla multi-languages system, not currently possible to do this like this.
The reason is that Joomla Item Associations system is not "yet" implemented in iCagenda (but planned for 3.7.x : www.icagenda.com/docs/roadmap)

For now, you need to create only one event for each language (set it to "all").
Then, you need to use a third-party extension :
- Falang, JDiction... to translate content in a independant component, and by using the content xml files provided for iCagenda : www.icagenda.com/resources/addons
- OR, easier if you already have a Joomla multi-languages set the "Joomla-way", you can just use the simple plugin "Easy Language" which allow you to set multiple language strings inside one form field, in a simple and flexible way : extensions.joomla.org/extension/easy-language/

Hope this helps ? (at least, until joomla associations system to be integrated in iCagenda...)

Best regards,
Cyril