The quild quest update time is found in src\core\variable.gd. The variable name is guild_quest_update_time.
Inability to remove dungeons is related to the Forget button at the dungeon. Haven't had that happen for a while. In the past, I could still use the Forget button in the Travel panel when the dungeon was selected. However the Travel interface has been reworked so I don't know if it is still possible.
Most of the day to day contact with Maverik takes place in the Discord channel.