This would be a new feature but it seems like such a critical feature. I can't tell you how many times I have started a print only to cancel it because I forgot to change the printing temperature.
The preview mode is excellent for determining feature types, active extruders and speed but it leaves off so much useful information! I would love to see an overlay that shows expected machine information along side the current moment in the preview. Things like "extruder 0 temp" "Heated bed temp" "Current layer height" etc. It's all information that is being processed in the g-code and it would be so useful when doing multi-material and multi color prints.
There's a lot of improvement in multi-material printing that could be had but this seems like the low hanging fruit. This would also be helpful when a setting is preventing an extruder from heating up properly or early enough
Example story:
I was recently printing PLA which were joined together by a NinjaFlex band to make everything flexible. Simplify gave me the customizations I needed to actually do the print which was amazing! But I threw away at least 3 half prints because I didn't get a temperature setting quite right and it didn't show up in the preview.