I've tested your bindings for a few days now. I'm using sendkey as well as sendcode inside my sitemap and inside rules. Everything's working as expected. I ended up using sendcode more because I found editing the json file cumbersome and converting an IR code is quite easy using the converter - this way I'm not dependent on the zMote webapp.
You should consider supporting a map file for IR codes. It would also be amazing if your binding included the converter (you can probably ask @urmilparikh for the code or specifications) allowing codes in the other more common formats, e.g.
NEC1 2 160 8.
By the help of your binding I've implemented one of the coolest rules my home might have seen so far, and it's dead simple:
rule "Sound System: Switch between PC input and Sonos input channel"
Item KodiPlayerState changed
if (KodiPlayerState.state == "Play") WZ_zMote_sendcode.sendCommand("38000,2,69,343,171,21,22,21,65BBBBBBBBBBBCBCBBCBBBBBCCBCCCCC21,1672,343,86,21,3730")
else if (KodiPlayerState.state == "Stop") WZ_zMote_sendcode.sendCommand("38000,2,69,343,171,21,22,21,65BBBBBBBBBBBCBCBCBBBBBCCBCCCCCB21,1672,343,86,21,3730")
What are your plans for further development? You should consider opening a pull request to get the binding into the openHAB distribution before Version 2.1.