Yes, this is also true. I have some strategies when I speak with others in trying to repeat their answer back to them, but with the correct grammar/vocabulary a

Yes, this is also true. I have some strategies when I speak with others in trying to repeat their answer back to them, but with the correct grammar/vocabulary and then answer their question and I'm pretty sure I picked this up from volunteers at a language meetup who did it to me. It not only provides feedback to the learner, it also helps to confirm that you're both on the same page with the information that was spoken. Generally, this works well for kids and adults without being demeaning but it's also important that everyone understands their role in the situation beforehand if possible. Regarding accent, I think it really is a matter of practice and will. I agree that it's harder as an adult, but we shouldn't allow people to use that as an excuse if they want their accent to improve. By no means is that a requirement, but it is something you should ask your adult friends if they are learning your native language. Though, I would argue this is probably not even worth it unless they are at a B1-B2 level. If they come from a similar language family (germanic, latin, etc) as you, then perhaps working on their accent at the beginning will prove fruitful, but otherwise, it's probably a lot of new sounds that they need to learn how to even say "correctly" before they can start adjusting how their mouth moves. For me, I've found that mouth training a little easier when I'm not spending 10 seconds formulating a reply in my head.