@iwojima @iwojima I'll help with that. Mitra can't see certain fchan groups because the value of preferredUsername field is not always valid (at least in the rest of Fediverse). For example in "fedi" group it contains a whitespace:
{ ... "id": "http://iwojima7cnn53jitsig4xjd23lchircbnu4yzuajdsclchiu3j2dbjad.onion/fedi", ... "preferredUsername": "federation testing",@eeee works fine on my end because it has valid username