According to his wikipedia entry Rabbi Sidon is a ger and the current Chief Rabbi of Prague and of the Czech Republic.
en.wikipedia.org/wiki/Karol_Sidon
If that’s not a position of communal (non-committee) authority, what is? However, I don’t know of any shul rabbis who are converts. Maybe there are some? If a community did want a certain convert as a shul rabbi, maybe they could appoint two rabbis as shul rabbi (the other one not being a convert of course), so in effect it would not be a lone position of authority. I do think that converts are not supposed to sit on batei din for the purpose of finalizing a conversion (which makes sense). But that doesn’t mean a ger can’t be a shul rabbi, because conversions normally go through a well-known beit din (there’s a list now that is approved by the Rabbanut), not just any three rabbis thrown together.