We migrated over from Netsuite last year. We use advanced projects. As part of our migration, our implementation team told us that bringing in transaction detail (or totals) on our historical projects was not possible, so all of our old projects show $0 revenue/expense/etc. As I’m more familiar with the system now now, I was thinking of ways to bring in some of the legacy detail. What I was thinking was to import a giant journal entry that has for example a credit to a new account called ‘Legacy revenue’ for all of our historical projects and then an offsetting debit to that same account, then associating the project with just the credit side of the entry. Thus the project would have a revenue amount but there is a net zero GL impact. Do you see anything wrong with that plan? I’m aware of the transaction line limits etc but it would be easy enough to stay under those for our use case.

From a GL perspective, this plan sounds right. I don't have experience with advanced projects. Regardless, I'd recommend testing a small sample in the sandbox to validate that everything works as expected.