Alright so here's my problem.
I'm not sure wether April should give a negative response or feedback if I use the wrong item on an object.
For example, if I try giving Stanley the CC instead of the timesheet, should April respond with a classic point-and-click answer like "Are you thinking with your arse?"
In my case, she just walks to the a position behind the object.
It's really quite annoying cuz I suspect that I miss out on important clues on how to solve the puzzle

In TLJ, if an inventory item is able to interact with some other object/person it will flash, otherwise it won't. What you have described is normal behavior.

If you really want somebody to stand there and mock your efforts, though, I'll gladly do so for a modest fee. :P