What's wrong with "Thanks, it is way better"? "way" was refused although the suggested translation was "Thanks, it is much better". Looking at the dictionary, I suspect a better translation than "much" would be "essentially", which is a bit different. Else, if "much better" is accepted/correct, "way better" should be accepted as well, no?
I think it is because saying something is 'way better' is more of english slang where as the proper way to say it would be 'it is much better" or "it is a lot better'
I'd say even "a lot" is somewhat colloquial and would not use it in a very formal setting, but it's not nearly as bad as "way", which I associate with surfers and 16 year olds.
Oh, I did not know I was using a slang or colloquial style here! Good to know! Thank you!