Hello Marvin,
Thanks for using our plugins and welcome to the forums!
For the time being we only provide WPML compatibility with The Events Calendar and Events Calendar Pro. Event Tickets and Event Tickets Plus are not yet compatible, it is on our long term roadmap though.
In the meantime, it is possible to partially use Event Tickets Plus with WPML.
However, the downside is that for now there is no way to create a truly multilingual ticket.
The end result is 1 distinct ticket for each language. This means that no sync of stock is possible until full compatibility becomes a reality.
If you have any further questions, let me know.
Cheers,
Andras