They should have an impact as far as I know.
Xenophobia has an impact on your relations to other aliens. If you a xenophobic you will increase relations to other races (not your own if you have any other than yours). I'm not exactly sure what Diplomacy does but translation will help with your translations with other races. Sometimes you will not be able to do this and it actually can happen that you fail with ordinary races to, at least I remember that happening to me once.