Thanks for the report, I already found the source of incompatibility between MessageActions and QuestLog, luckily it's on my side so I should be able to correct it with a patch!
Viewing post in Feedback and Oddities
The cause is in the QuestLog Info window (the one drawing the quest description and informations).
To add the two buttons for Tracking and Log I turned it in a "Horizontal Command Window"
It's a trick I did to save time on the button generation and to be able to use the built in navigation of RMMZ
While it works ok without MessageActions, this plugin add a fix to calculate the button text and it works flawlessly in a "normal" horizontal command window but in a "special" window like QuestLog it generates negative X values for the text
All I need to do is to assign a ProcessText function that recalls Window Base instead of Horizontal Commands Window and block the alignment fix of MessageActions only for the QuestLog Info window commands