For issues you find with the Switch and Console releases, please follow this link and give as much detail as possible. This is the speediest way to get info to Pipeworks and get a hotfix in the works.
For issues you find with the Mobile 1.3 update, please follow this link and give as much detail as possible. This is the speediest way to get info to DR Studios to look at your issue. Also, some troubleshooting hints here.
Terraria 1.3: Xbox One Submission Approved! Launches Monday, February 5th!
Current Terraria mods (tModLoader tAPI) do their stuff by directly changing the game's code. This is not allowed on console as that would open up the possibility of hacking the system. The console makers (Microsoft, Sony) won't EVER allow this.
Modding in games such as Fallout 4 work differently, mods can only change things indirectly through scripts that have limited functionality. Mods are limited in what they can do.
Adding a similar support for mods in Terraria would require rewriting the game from the ground up. That is simply too much for an indie developer such as Re-Logic. They don't have hundreds of people like Bethesda have.