Its just for Wide midfielder ? Or for other role ?
No, mate... I haven't been noticing that the assistant manger changes any other roles when I use "Instant Result", probably, it's because usually players that are used for other roles have "acceptable" rating for these roles in the eyes of any assistant manager and it doesn't pass the minimal threshold level when the assistant manager starts to act and change the role.
"Wide Midfielder" role is a very specific role, it has full customization and it can be tweaked into Winger, Inside Forward or any other role but the assistant manger isn't capable to recognize all modifications that were made to the role and he always evaluate it based on the default attributes for the role.
At this screenshot you can see highlighted attributed that the assistant manger uses when he evaluates players' suitability for the Wide Midfielder role:
Here are the highlighted attributes from the screenshot:
Tackling
Anticipating
Determination
Crossing
Passing
Decision
Positioning
Teamwork
Work Rate
Stamina
As you can see the set of attributes look totally weird, especially, these attributes: Tackling, Positioning, Determination...
We usually tweak the Wide Midfielder role into Winger or Inside Forward so we need a typical winger or inside forward for it... someone like Messi, Ronaldo, Bale, Neymar, Hazard and so on... of course, they won't have these attributes Tackling, Positioning, Determination, Work Rate and Teamwork at any decent level... further more they have these attributes at minimal possible level so any assistant manger "thinks" that these players are just totally awful for the Wide Midfielder role and when you use "Instant Result" he changes their roles from "Wide Midfielder" to something else what would be the best for them according to "his vision", usually it's a role that has the highest rating Winger or Wide Playmaker.