You intervening can help a bit - but intervening shouldn't mean punishment (which is what people usually mean when they use the word "correction"

). It would be FAR more effective to intervene by removing her from the situation when she's behaving badly, take her off on her own for a little bit and do some quick training exercises - then let her back to play again. If you need to, keep stepping in and taking her off to do a little work. Eventually she should start getting the message that if she doesn't play nicely, then she doesn't play at all (the training exercises are really for avoidance of boredom or fixating on the situation you've removed her from, and also for having her work and receive rewards which can help improve her frame of mind).
That's one thing you can do. But I'd also recommend that you consider finding her some play time with another dog (or more than one other dog, though not necessarily more than one at a time) that is (a) an adult (definitely not a puppy) and (b) a confident, strong and good natured animal. What this dog is for is putting her in her place
nicely but firmly
All adolescents (and yours is definitely an adolescent) need adult guidance to learn how to behave in social situations. Adolescent dogs, like humans, can be a bit in-your-face and it takes time to learn more sophisticated behaviour. Generally they DO learn - but as your trainer suggests, it can be via a bad reaction from a less tolerant adult. Thus, if you know anyone with an adult dog (doesn't need to be a big dog, but it does need to be a confident, calm and dominant dog) that you can use for socialisation and education of your adolescent, then scheduling some regular playtime would be a very good idea.