For other transactions that you'll need to import, I'd suggest contacting Wave Accounting support since it's a third-party application. They'll provide you details on how to do it on their end. Also, any questions or concern related to migrating data to QBO is best handled by their support.
Alternatively, you can find third-apps that can transfer your data to QuickBooks. Just click on the Apps menu on the left side of your Dashboard or access the App Store to find one. Feel free to visit our Move to QuickBooks Online page for more insights about what you need to know about bringing over your data.
I'll be right here to continue helping if you have any other concerns or questions about QuickBooks. Assistance is just a post away. Have a great weekend.