I tried your method on the original US layout where I needed to change only few chars for additional Croatian ŠĐČĆŽ letters (brackets and so) but without success. I tried with and changed CZ, es_EN, en_US, and asusec.kml but result was always the same. There was no change no matter what I changed and what I choose for the kb layout or language. Frustrating. Do I need to use RU instead?
The only thing I managed to modify is the LOCK (or SLEEP) key to become DEL by modifying the asusec.kl file.
Where I'm going wrong here?
UPDATE: I was copying and pasting the error... Huh, so many hours because of one apostrophe.