The problem with running these adventures is that you have to be a pretty hardcore Mystara fan to have run these in the last 15 years. And if you were, you were probably running your own campaign based around the Almanacs. Thus you wouldn't be running these adventures.
There are two reasons I haven't played/run these adventures:
1. I haven't played/run many modules. My groups have just never used a lot of modules. I've been disappointed with the results nigh every time I've run one. The ones that I have played/run have been AD&D except for B1 (& recently B4 & X1).
2. I don't think I've ever had a PC higher than 9th level or run a campaign that reached a higher level.