They crash because WC3 is a buggy, poorly documented mess.
Some poor Blizzard employees were forced to maintain Warcraft III after a critical security exploit was discovered involving typecasting code to allow arbitrary code execution. This is when they added the GetHandleId, the string hash, and hashtable natives we are so fond of today.
When adding these new features to GUI they saw GUI had "Region", "Ability", and other such types so decided to link it to them, after all people might find it useful. What they failed to spot was these types are a lie. GUI "Region" is actually a JASS rect, with JASS region being something completely different and entirely unsupported in GUI. Like wise GUI "Ability" is actually JASS integer, with JASS ability being an entirely unsupported WC3 type, probably representing internal functionality that cannot be accessed (no natives to manipulate) or a relic from early days of development. Non the less GUI actions were added to reference these unsupported in GUI types. As one knows the editor crashes as soon as they are processed.
One cannot really say the guys who made the mistake were to blame. Ultimately the blame falls with the developers of WC3 GUI who made it so poorly written, confusing and error prone in the first place. Fortunately SC2 GUI is considerably better engineered with much better linking between GUI and Galaxy script.