This has been asked and answered many time on the forum:
No, you don't have to restart Couatl and you surely don't have to rebuild the cache when the simulator starts, just to see jetways.
On some airports, with lots of jetways (and surely EHAM is the prime example) AND if your system is overloaded by other addons, it might take a bit longer than usual for jetway to show up, so you might just have to wait.
If you have a 3rd party airport that *switches* between different AFCADs with an external utility (and surely EHAM is the prime example of that), depending how that utility is made, you might have to Rebuild the cache, because to speed up the loading, we don't check each and every file in the system, but only the last modification date of the folder the file is in, which is way faster to do, but might not always detect file RENAMES. That's why you might have to rebuild the cache when switching AFCADs.
And, of course, if the AFCAD switches, you need a separate GSX .INI file for *each* AFCAD you can possibly switch to, each one with jetways of course.