On one hand this seems unnecessary because links and search takes care of all of this, but at the same time using terms in the URL more natural to a particular language would be more memorable and may help with search. I think it is a matter of what you want to do. I am a tech guy that studies and uses automation and this seems right up my ally, but if you do the manual work to cover this, it really could take time. I think there is search value using the natural language URL and you can reduce some of the work by not having both airports and aeroportos when aeroportos is more natural, but if you drop airports you may be dropping other users such as travelers.
You can create canonical link for all of this to avoid duplicates where it applies.
Another thought would be to have the page appear in the natural language for pages such as aeroportos or at least use a more natural English for these pages.
If you can do the work, from an SEO perspective, this is something that I think can broaden your search presence. While on one hand Google handles aeroportos as being the same word as airports, you would rank higher using pages/terms aeroportos. As well, you can conceivably broaden the number of links in the SERPs. One way to do this is to link your airports page to aeroportos and vice versa. Lately, I have increased the number of links per page in the SERPs from 1 or 2 to 2 to 6. As well, for some searches, I have dominated the SERPs for unique searches. You may be able to do the same. But I think you would need more than just a URL to do this. You would at least need a more natural English on the pages as well.
Keep in mind that people feel more comfortable in their native language even if the page is still English, having the appearance that the page is in a more native English, can really drive the number of people who may click on your link as opposed to someone elses.
My suggestion is to explore this idea by taking a few of the most pages/URLs you think would be the likely to be effective and creating a few scenarios (URL/pages) that fit the concept and see what happens. You can try new ideas and measure results as well as check out how much work this would be and see if it is something you can do and/or something you want to do. If it does not work out, it is only a few pages you can 404 or 301 redirect and remove from your site if you decide not to proceed.
All and all, I think this is a good idea worth at least testing for a while and see what other new ideas come out of it. I think you will be surprised.