Status of Spell effects
 

Is it possible to query the status of spell effects in any way ?

Not sure exactly what you're asking.

The Spell Effects window is hard-coded, meaning there are no dynamic data types for effects current on yourself.

The Maintained spells do have several DDs: Icon, Name, Duration, Target. The trouble here is that the icon possition changes dynamically, so its difficult to use this data for anything other than labeling.

In both cases, the icons are directly scriptable, so in theory it is possible to use OnHoverin and other events to pass info to something else.

The aim is to write a uimod peace which reads some specific maintained spells and look if they are casted or still have to be casted. So the ui mod would look up if for example 'Sprint' is active and decides whether it activates it IF mana is above 50% or deactivates it IF mana drops below 50%. I hope this is possible without a loop since loops (while cases) do not seem to be implemented in eq2ui scripting.