The notion of "willing suspension of disbelief" is one of the most misleading phrases in the literature of writing (right up there with "show don't tell"). It is very much worth reading Tolkien's On Fairy Stories, in which he offers an extensive critique of the concept.
Tolkien's argument is essentially this: a story involves immersing a reader in a sub-created world. Their participation and belief in the sub-created world depends on the internal consistency of the world, not on its correspondence to the real world.
Secondly, stories are lenses, not windows. They exist to focus the reader's attention on certain aspects of the human experience and one of the principal devices by which they do this is to simply omit many of the details of ordinary life that real people would have to deal with. Thus characters seldom eat except as something incidental to a meeting or a party. They virtually never have to relieve themselves (except in broad comedy). Virtually no use of computers in all of literature is remotely realistic. Crimes are not really solved in a day. Etc. etc.
A story needs to be self consistent. Whatever it says or suggests about the rules of the story world must be followed consistently within the story. If you decide to ignore language barriers in a story, go for it, but make sure that there is not anything else about the way the story is told that suggests that they matter.
Note that when I say "story world", I don't mean exactly what the folks who indulge in that odd hobby of worldbuilding mean. It is not about creating a world with self-consistent rules and then setting a story in it. It is much more about the conventions of the telling itself than the objective laws of a world, real or imaginary. It is a tacit compact between the writer and the reader that we are not going to concern ourselves with whole classes of practical problems that would otherwise slow down or get in the way of telling the parts of the story that we actually care about. This is not a rare or unusual thing. In fact, it is probably universal. Certainly no contemporary TV show could function without this convention. (In the real world, for instance, all the characters in any cop show would be invalided out with severe PTSD by the end of the first season.)
If you have not noticed that storytelling works this way, well, that just shows how ingrained this feature of storytelling is. We are not consciously aware of it most of the time unless it breaks down. But it is there in everything we read and watch if we only take a moment to look for it.
So, if you want to ignore the language issues, ignore the language issues. Just make sure that you tell the story in a way that people accept (without particularly noticing) that languages issues, like going to the bathroom, are not something we are going to concern ourselves with in this story.