I apologize in advance for the ridiculously long post, but I had several inter-related questions so I kinda wanted to keep them together as opposed to breaking them into several more-reasonably sized posts.
We have several GMs in our group, so we have about 3 campaigns going on different nights - currently I’m the only 2E GM, and my campaign’s pretty low level so far. My friend runs a 15th-level PF1 campaign, but he’s interested in converting. So as an experiment I offered to come up with a series of encounters for his current campaign (a temple of Orcus, so kind of demon-y) for him to run as a one-shot, with everyone temporarily converting their characters. (I would play as well, but keep silent during any decision-making.)
So going by the encounter-building tables, it looks like a 17th level creature would make for a good boss fight against our 15th level party - I chose a marilith. I then used the Pathbuilder 2E app to convert a couple of our characters, just to see how things might line up (the party’s light-armored archer-fighter and my own draconic-bloodlined sorcerer.)
At first, numbers for our characters looked incredible - ACs in the 30s, saves in the low 20’s, mid to high 20’s for skills that you wanted to excel at. But then I compared the numbers with a couple of the encounters. The marilith (granted, boss fight so should be tough) has an AC of 40 - archer/fighter shouldn’t have a problem with that, but my sorcerer’s spell attack bonus of 26 needs a 14+ to hit, and its appr. +30 saves vs. my 36 DC seems kinda mismatched - although I totally get this is offsetting 2E’s lack of spell resistance. And I’m hoping a lot of spells with “take x on a successful save helps out as well. But its attack bonus of 35 seems to suggest LOTS of successful hits, as well as its own save DCs of near 40 means its damaging spells are extremely likely to succeed.
Does this all balance out in high-level play & I’m needlessly concerned? Is the idea that you do get hit a lot more, but you now have more HPs to cover it, and with 4 or more party members spreading out the damage taken and with numerically more actions it all evens out? Or am I totally messing up the character conversion and numbers for 15th level characters are generally higher? Or am I reading the encounter building table wrong and 17 is just too high?