We were off to Prague before we read your message, but we did have a go at the Royal Road. We haven't been in touch with the owner yet as recuperation is needed. We achieved all the clues accept one, which gave us two possible answers depending upon how the "frame of the plaque on Charles Bridge was made up. Putting either of the two numbers into the final location, took us to the area of Mozarts Museum on the west side of the river, but GZ was inaccessible. We thought it may be within a fenced off area with what looked like gravestones, but the gate was chained up - the gps still read about 100m further on which was a very, very steep hill full of trees. We tried to get to the other side, involving yet more climbing, but it was a building site with razor wire fence.
All in all, a very exhausting search in which we must have walked about four miles up some steep hills. Our trusty gps was acting up all day and proved most unreliable. One thing it did bring home, is that a normal walking compass will be a must in the future. There's a good chance we were no-where near the final area!!!
We had enjoyed the multi cache up until the miserable end. From this description, were we anywhere near the cache??? Cheers.