Changing the measurement system cannot affect the absolute value used by the "Increase/Decrease Indent". Under any measurement system, indents are increased/decreased by the same absolute value measured in so called points (1 point = 1/72 logical inch).
You can request features (as a matter of fact, there is a separate forum section meant for feature requests). But we cannot give you any timetable, or even tell whether a particular feature will be implemented or not.