I understand that issue is know but it is not clear whether the problem is solved.
I had this issue on 4.10 and upgraded to 4.11 where this error is mentioned to be kinda fixed. The only difference is interface func instead of custom event.
Info_display that returns User Widget ref is interface func
Blueprint Item paranted to Actor
Blueprint Item_Equipable paranted to Item
Blueprint Item_Weapon and Item_Armor paranted to Item_Equipable
Overriding Info_display in Item and Item_Equipable works fine
Overriding in Item_Equipable’s childs causes ‘This is not a TRASHCLASS_Item_192’ error on ‘Parent: Info_display’ node