I have done some more testing:
If I remember correct, when MT4 is launched correctly with tickstory it only shows the exported instruments in the Symbol list of the Strategy Tester. When I launch it, MT4 does not launch through the patchlets I think. Title bar does not say "Launched with Tickstory" or whatever it should say there. It also shows all the regular broker's instruments in the Symbol list.
On the other hand, if I run a test with a FX instrument of which the name is the same as the one in the actual list (i.e. AUDCAD) it runs and I got 99.9% modelling quality. However, for some reason it also happens that it says that the .fxt file is read-only in the Journal and the Strategy Tester does not run.
For exported Symbols with a different name (i.e. DEUIDXEUR.fxt), they don't show in the Symbol list of the Strategy tester.
To me it really seems like the tickstory launcher is not working correctly.
Thanks for your help,