In the meantime, a user on the Thomann site has written this:
The granularity of the sliders is unusable with a minimum of 4,688ms (at least for my purposes). 4.688ms corresponds to 1.61m at 344m/s speed of sound, much too much for a precise runtime alignment between woofer and tweeter. I then came up with the fact that you can also type in numerical values for the delay. But you have to find out for yourself which granularity is possible. The field has 3 decimal places (whereby the point must be used as the decimal point, you can't use a comma), so it should theoretically be possible to make entries with an accuracy of 1/1000ms. In fact, the smallest possible value that is accepted is 0.021ms, anything below that is reset to 0.000ms. The next larger accepted values are then 0.042, 0.062, 0.083 etc.
In 0.021ms, sound travels about 7mm, which means that a reasonably accurate runtime compensation between drivers that are not quite the same distance away is already possible.