I don't think so. I'm sure Openreach could get the VDSL2 line rates and other data from the DLM.
The BT speedtester uploads the results so that they can be seen by the faults handling systems. Apart from retrieving your IP profile, the BT speedtester is really for when your line rate is high, but your download or upload speed is lower than your line speed. It's not really for the line speed itself being lower than it should be. It'll always show that "acceptable range of speeds" according to whatever the current line rate is.
I thought the initial estimate could be partly based on the performance of nearby lines, but of course if you're one of the first few people on the cabinet, there aren't any currently on FTTC, so it could only be based mostly on the line length, and any data they have on line quality, if there is any.