In English, the word in is used fairly commonly, as opposed to my native language. You can say sentences like The book is written in Esperanto. where in refers to the text’s language (Esperanto). Google translator says it would be La libro estas skribita en esperanto. (I used translator because I just started learning. I mean, skribita as an adjective?)
On the other hand, in English it can also be used as in The cat is in the house. which means the cat is currently inside, similarly to La kato estas en la domo. However, it can also be used as The cat went in the house. which could be either La kato iris en la domo. or La kato eniris la domo. The second seems better, as it gives the direction, kinda like German with accusative/dative.
As a non European language speaker, can I expect to use always uses en where I would use in in English, or are there exceptions?
I'm curious about your choice of examples and learning materials. Google Translate is not a good source to learn from and two of the three examples you have about cats and houses are grammatically wrong. If you need help finding good materials to learn from, please do ask.
With regard to your question about en, PIV (the most definitive Esperanto dictionary) list 8 different meanings for en.
So, yes, there are many uses where "in" and en are the same, but for sure this is not the case 100% of the time. Esperanto doesn't have an expression like "the in crowd". There are also fairly common cases where you will use en in Esperanto where you use a different word in English.
Better, though, at this point not to get distracted by these fine points. Learn a little more Esperanto first and if you find an example that doesn't make sense, dig into it a little and ask questions.
Correct answer by Tomaso Alexander on August 24, 2021
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