I used the X-Wing Combat Flight Instruction. It's very good.
You're right, Moslo can do the trick if the error isn't in the script itself. Sometime I'll just for fun check how many errors the localization company introduced into X-Wing and Tie-Fighter. Wonder how they could introduce such errors, all there was to do was translating briefing screens/in flight messages/cargo of ships etc. Really not much. At least the original scripts for missions should remain untouched. I think with structural changes, the original engine is not too bad. Remains at least perfectly playable at ~166 MHz.
One mission in Tie is so screwed, you will not believe it, but there are parts from the original LucasArts' editor help file and other crap in it. The filesize is 160kb if I recall correctly, while the clean file (which I rebuilt) has only the usual 5-7kb per misssion. Mission still works, but as was buggy and impossible to edit, had to rebuild.
Then there's loops like 'Z arrives if Z is hit'. One mission in Tour 2 of X-Wing, the only where you can attack an ISD without launching of TIEs. Clearly the loop should be Z arrives if ISD is hit'... couple of similar errors are in it. So I guess I own the only almost perfectly bugfree edition of X-Wing.
Almost, because the localizers screwed up the ranks. When you access the registration screen it says e.g. Captain... and in the pre-flight roster it says Colonel (the 2 letter abbreviation) and vice versa. And one or two spelling errors in the Historical Missions title screens.
If somebody could change it, would be great. I don't know which file it is, one of the LFDs, there's even an editor for most of that, but doesn't work with my localized file, editor says it works up to X-Wing 1.2 while I have 1.5 in German. Just crashes.
If anybody has good knowledge of these, I can send you the original file, tell you what to do. Or name me an editor which accepts all kinds of LFD files, where to get it, I can try to fix it myself.
Not important, though it would be an accomplishment to finish it with 100%.
It's not even the best utility for it. There is a Windows version, too. So it might even work. But it causes lagging with X-Wing and Wing Commander. I found AT-Slow is much better once you get the slowdown rate right, it uses increments from 1-1999 instead of percentage. So it differs depending on CPU and speed, but once you got it right, it's really good. Almost perfect. Can use percentage if your CPU is supported, which mine isn't. Tried almost all of them. No lagging at all with AT-Slow.