It's half a compiler bug/oversight and another half questions/comments/suggestions *gets shot* Thus why I didn't report it in the bugs section.
It doesn't seem like the compiler recognizes anything about InputPressx variables. Did you (as in the devs) only implement them in ZASM or something?
Wouldn't it also make sense to add InputUnpressx variables to go with the InputPressx variables?
Also: It seems InputEx1-4 compile just fine. You should probably mention them in zscript.txt...