I don't believe that is a problem. If terevos@lemm.ee follows the same rules as r/reformed (which he is also a mod of) I believe the general stance is different views are welcome, but this can't be a soapbox (for lack of a better term) for those different beliefs.
Yeah, mainline and liberal are welcome. We will keep the same rules as r/Reformed though, so we would ask that you not advocate for things that are against the historical consensus on matters of Christian ethics