Impressive response speed.
June 11: Posted the problem: 5.2 No intro quest for custom souvereign. (this thread)
June 25: Found the solution myself and posted it: Fix for the 'No intro quest for custom souvereign' bug
July 10: Stardock answers in this problem thread with the solution that i myself have found.
The support guys at SD really need to learn to speed read, because the above means that reading (the solution which is two lines of text) went at a staggering speed of one line of text per week.
Lets hope there is not an outstanding bug which has a known solution of 52 lines of text, because then SD will need a whole year to respond.