Hi, in the math panel of the Dutch version of LyX 1.2.0, the button for the Greek characters says "gamma rho iota epsylon kappa sigma". I suppose it's derived from the English "gamma rho epsylon epsylon kappa", which is written properly, but in Dutch, it is wrong. The g of greek is soft and can be written as gamma, but in Dutch, the g of grieks is hard. There is no English equivalent, it's kind of a growling sound and should be written with chi. That is the Greek character which looks like an X. The sigma that is written at the end of grieks, should be the other sigma. It sounds exactly the same as the sigma you placed there, but in Greek, a sigma placed at the end of a word, should be written with the other sigma. This one can hardly ever be found in a mathematical equation, but it is in the menu under the button, just to the right of the sigma you used.
I did not mean to be highbrow or so, but if you put so much work in making this nice package, you just want it to be right and I hope this can help you. Good luck! Vinay