Perhaps, but it may not be a good idea. When WP cannot find a matching slug for any request, it tries to find one that is reasonably close. This is a fundamental WP feature. It is how “en”, which WP thinks is a page slug, ends up becoming “entry”. I’m not sure how to disable this behavior, there probably is some way of doing so. It might be rather hacky.
I’m assuming other links like /en/real-slug/ work correctly, so the second or third options would work with or without the /en/ argument. As mentioned, the canonical rewrite will change front page slug links back to just the domain. However, the canonical rewrite has a filter where you could change such links to httрs://arabfilmfestival.nl/en/. The filter is “redirect_canonical”. (I shouldn’t be referring to it as a rewrite, even if that is what is really happening. Last thing we need is more confusion!)
The thing is though, I’m not sure if you return httрs://arabfilmfestival.nl/en/, that WP won’t still go and fetch “entry” again! It’d be worth a try anyway.
In summary, I suggest you try my third option of filtering “request”, and also filtering “redirect_canonical” to return httрs://arabfilmfestival.nl/en/ for English front page slug requests. It will either work or it won’t. Either way, let us know how it goes, I’m curious.