After several years of development, we setuped the mailing list for HSLayers again. It was here about two years ago, but then, since we had to move our servers, it was gone. Now it is back and you can register via mailman at https://lists.hslayers.org/mailman/listinfo/hslayers
We did not distinguish between -dev and -users mailnig lists yet, because we do not expect big traffic. Once this situation will change, we will create more lists if needed.