For the past couple of years I've been studying French and German via the Duolingo website. It's been fun and educational in more ways than just improving my knowledge of those two languages.
Duolingo.com is a US based website so when it was first set up - and I began learning there very soon after that - it was very US centric. If you used a phrase or spelling that varied from the US version when you translated something you were likely to be marked as incorrect. It was extremely annoying as you can imagine but, thanks to them having a system where you could report such matters, things rapidly improved - although a few intractable issues remained for a long time, hardly surprising when much of the work is done by volunteer moderators. They now accept a number of regional variants in most areas - even if I'm still pushing them to accept a couple of Australianisms like 'How are you going?'.
The interesting thing, though, comes in the discussion sections where you can ask questions and have them answered by the moderators or other students and comment on various matters. This is a very helpful part of the learning process but it's also where people can get testy and where the many and varied differences as to what constitutes 'correct' English shows up. Many see their regional variant as the only correct usage and sometimes they defend this fiercely.
As I have a degree in English and am an English teacher by profession, I'm often tempted to join in these fiery discussions but I've learned a thing or two about the internet over the years and so, unless it's a simple grammatical or structural issue, I bite my tongue - or perhaps that should be hold back my fingers. It's by far the safest way as many of these commenters - who I presume come from a fairly insular background where they rarely meet people different from themselves - are so convinced they are right that there's no likelihood I'll change their minds.
Fortunately these people are the minority. One of the things I really like about Duolingo is how most people want to help and will go out of their way to do so. It makes for a pleasant learning system and one that, now I'm close to finishing in both languages, I will miss.