I'm in a similar position. I'm a native English speaker but the main site I'm working on is in Portuguese because the competition is far lower and I'm already ranking some articles with close to zero backlinks, apart from some blog comments on portuguese blogs and reddit comments on the Brasil subreddit.
My domain name is in Portuguese. I've written most of the 45 articles myself, about 10 were outsourced.
I also have a domain in English which is effectively the same site. It looks different but the articles will be the same. Maybe there will be some that are specifically for the Portuguese one but not many.
I have ignored this website because the competition is far too high. I only have about 12 articles on it, so that means I have about 33 articles that can be added fairly easily.
I think I'm going to ram up the content on the Portuguese domain and so I might as well put the English versions of the articles on the English domain.
I will probably continue to post the Portuguese content first, then every so often hire a VA to post large batches onto the English one.
If I do build backlinks, it will be Portuguese ones to the Portuguese domain, and English links to the English domain, is this correct or does it really matter?
As asked before, the only downside I can see is that Google MIGHT penalise the English site because it is effectively copied form the Portuguese one, as the content goes on the Portuguese one first. But that wouldn't be the end of the world because the English one is so hard to rank.
All content is manually translated, not spun.
I also think it would be wise to use as close to 100% different images on each article, either by using a completely different image or changing them on photoshop using filters etc.
If all internal links are exactly the same on both is that a bit risky, or am I over thinking it? I guess I could switch it up a little bit too, some internal links are a bit arbitrary so can switch them, others are very improtant and relevant.
Very importantly the RPM on ezoic etc is terrible on the Portuguese one, maybe $2.50/$3. If I manage to throw on 200,300, or 500 articles onto the English one then I have a chance to rank from more tier 1 countries on Ezoic and get that sweet, sweet delicious higher RPM for effectively the same content.