This is going to have to be a hard "no" I'm afraid. But let me take a moment to explain why, as I do get where people are coming from on this.
Firstly, generating gameplay in Renpy is pretty tricky. At the moment the player has to take a moment to look at what they can see and think for a mo. Finding things, unless they are fairly key to the game, is a bit of a challenge (the stuff you need tends to be quite easy to pick up I feel or at least is so logical it shouldn't really be that difficult). So the hidden items, finding them has an element of reward as you're on your own to pick them out using just the visual clues.
If I made these elements highlighted then there is no gameplay element whatsoever. All the player would have to do is to put their cursor in the top left hand corner of the screen and whizz it up and down, left and right and bingo. Things flash for them to click on. I feel, and I accept people may disagree with this, is that this is a worse system for now it's not a challenge for the player to find things but instead becomes a grind of just moving the mouse around the screen until they are told they can click on something.
Secondly, and far, far, far more importantly, the time taken to go back and make some 200 "flashy" images for all the clickables and then re-jig the code will take time. Quite a lot of time too. And that's time that could be spent on Five instead.
So from where I'm sat, although I both appreciate and think it's great people want to find everything, I'm ending up with poorer gameplay and delaying Five. And hence the "no."
