Thanks for your kind words, Jamie. I cannot really say much about "film density". Maybe the colors shifted with different density, and the grain structure changes. I am just using a LUT and adding elements from my PowerGrade and grade it. I like the "filmconvert" plugin (But I rarkly use it.).
The colors from filmkonvert are excellent. But for grain I don´t care if the highlight rolloff emulates film 100% correctly. The grain itself should look good. And if the wall you are shooting is a little bit brighter or darker that will also have an impact on your grain structure. And the light on set The grain itself can be very different from shot to shot. I think it is good to get close to the original film look. As close as possible. But also keep things simple. Don't overthink every element to much.
I like the Quote "Perfect is the enemy of good".
if you google the meaning you find something like "The Best is the Enemy of Good means that close is sometimes GoodEnough, and exact is far too costly."
For ColorGrading. If you spend weeks, month, years fine tuning "one thing" ...so what. Yes. It is important to observe, to actually look at "behind the scenes" (This is what I am doing on my website). Look at the colors. and look at all the elements (grain, color, gate weave). Try to replicate it, if you like it. Try to get close. If it "feels" like film, you made it. Even if its just 95% accurate. Use the tools to be creative. Prqactise. Work on projects. Film is always changing. If you want that 100% .. shoot film. If you want to emulate film, try to reach 95, 96%, no need to reach 99%.
Hope that makes sense.