As a practice, you should give your result set table names the same name as the table names you used when you designed the query.
I will read data into the same typed DS definition that I used to create the report schema, so I never have to worry.
If Mere Mortals doesn't allow you pass in your own definition of your tables names from a typed DS, I'm guessing you'd have to "name" the names afterwards. (It's been a few years since I used MM).
However, I believe that in the absence of meaningful names, you might be able to set the report dataset tables based on position/table number within the dataset. So if your report definition used 3 tables, you can pass in a dataset at runtime with a dataset that has the 3 tables in the same order. I don't care for that practice, but it *should* work - at least it worked the first time I ever tried it.