Hi HInoue,
If you value your time here on earth, I recommend to never implement a complex dialogue system in UMG and Blueprints!
Your data can be adapted for the system in a few different ways, it would be a matter of changing 2 or 3 overridable functions in an inherited BPC_Dialogue class:
The text is retrieved through an overridable ‘TArray<FDialogueItem> GetDialogueItem(FName textKey)’ and ‘TArray<FName> GetDialogueRowNames’ functions, if you can convert your data to fit DialogueTableItem (a blueprint structure, so the converter must be in blueprints) and either change the ‘GetNextState’ function and ignore the GetDialogueRowNames function, or implement the GetDialogueRowNames.
Let me know if you run into any trouble if you follow this route