I think you can update to B009 by downloading it from Huawei and then using the "force update" method as described in the instructions for the rollback procedure. Links are in post https://forum.xda-developers.com/showpost.php?p=75570381&postcount=512Where can I find either B009 or B010?
I think you should NOT install the C300B900 package, it is explicitly only foreseen to be installed over Nougat ROMs!
From B009 my DL09 tab (with LTE) then directly updated to B303 the official way. Only for the update to B307 I had to use FirmwareFinder.