Main Trial Difficulty Charts (solo)
Disclaimers: This is assuming that you are running a rig other than stun/blind or are going rigless entirely, as the difference those two can make in finale's and other tight sections are night and day. Assume if you're running either of these everything drops one level.
This is also assuming you're playing on intensive or psychosurgery, I'm an escalation enjoyer so my experience with these trials will affect how I view their potential. I have played most of these trials dozens of times, but I have only played Silence the Idol maybe 4 times, as Erik makes me too sad - so it will probabky be the least accurate.
I'm also if course having the caveat that this is playing solo - some objectives and sections can be trivialised entirely with a second+ player.
And finally - the difficulty scaling is not necessarily based on how likely you are to die, but how likely you are to be dealing with constant encounters and how precise you must be. Push 2 of PtM for example can be trivialised with good RNG, but other times you can have the giant and cocaine grunt in the worst possible positions. A difficulty of 1 means you have pretty much no threats whatsoever apart from idle grunts and you can pretty much do whatever you want. A difficulty of 5 implies you have to be constantly on your toes, lots of enemies, enviromental hazards, little hiding places, lots of brightness and objectives you must be very precise to complete.