I wouldn't worry at all about scores on prep company tests. If you scored 730 twice on official tests, and if those scores were fair (you didn't know many questions in advance), then your true level is almost certainly in the 720-740 range, regardless of what any company test says.
A lot of my students have had a similar experience to yours - they score 750 on official practice tests, and 650 on some company tests. They then invariably get 750 or thereabouts on test day. There are a few issues with company tests, but one problem is that company tests are often measuring something different from what the GMAT measures. Some company math questions, for example, are 'hard' only because they're complicated and time-consuming. Real GMAT questions are almost never complicated or time-consuming, if you know the best way to approach them. So the company test might be rewarding the person who is great at algebra and who is really fast, while the GMAT is rewarding the person with deep conceptual understanding. The scores on the two tests will be modestly well-correlated, because a person good at concepts will often be good at algebra, and vice versa. But there will be quite a few test takers who will do much better on one test than on the other, and I'd guess that might be the case for you (it's hard to know for sure without more information, of course).
A 730 is a great score, so it sounds like you're doing very well. Good luck!