Hello Thijs! Thanks for getting in touch.
Those are good questions. First off, I’m not aware of any specific issues or conflicts related to the Avada theme. However I did a quick search through the forum and found some past topics where others had some difficulty making customizations when using that theme. That isn’t to say there are not conflicts, but I think it would be a good idea to install the free version of The Events Calendar and give it a try to see if it works well for you.
You also asked about a Dutch translation. You can check our list of available translations. It appears Dutch is translated up to version 3.7 of the plugin, so I would guess that you may come across some strings that will require additional translation.
Does this help answer your questions? Please let me know. 🙂
Cheers!
Geoff