Thank you Mihai,
In the code and in the error it exactly seeks for x2goclient_tr_tr (or x2goclient_tr_TR depending on version) file. However, when I read the link you sent, I got that there can be another wrong character in the name. In this link it says x2goclient.tr_TR or
x2goclient.tr are the correct front names of it. So, there can be an underscore or dot character problem.
Well, I have forked the code to my github repository today, and I will have a look at it when I find some free time. So, I will inform you back about the further work.
Best Regards,
Orkun BALCI