DD tables are not only mandatory, they are more then that. They are data Dictionary tables, building blocks of system.
Take a look at DD02L (Tables), DD01L (domains), DD04L (Data elements) tables...are all of them in synch ?
Maybe there's some dependency between for instance DD01L, and DD04L with DD03L that you have to take care about ?
For instance, in MS SQL sometimes before some mass-bulk inserts we have to disable foreign key constraints , because you cant insert data element if domain it references does not exist in DB allready.
I'm not sure how Hana handles it in SLT, didn't have the chance to play with that as much as I'd like.
But I thought its worth mentioning.
Have a Nice Day