These threads are funny because there's always one or two posters who lurk in them for _hours_, not adding much, just upvoting every single pro or con post (protip: some of the posts you think are aligned with your perspective aren't - that's the downside with knee-jerk clicking

)
Anyway ...
Doesn't matter if Apple leaves these library files to waste space or removes them. They aren't compatible with iOS 11, so won't work. It's also quite possible that the A11 chip in the iPhone 8 and X doesn't run the armv7/32-bit ARM instruction set at all, just like it won't run 6502 or PPC code, so iOS 11 can't have any 32-bit code in it.
Yeah, I'm very interested in hearing about the architecture.
Why? If I wrote a perfect app when the system I was working on was 32-bit why should I come back latter and have to change it. I done my job, provided a program that delivered everything I promised it would. Yet after years of working fine Apple wants me to re-write it?
It rarely, if ever, happens like that in software development (speaking from 25+ years of experience as a dev/architect/writer). Software flips out and inherits bugs all_the_time. Underlying libraries change as the OS is updated, dependencies break, performance issues arise over time - I'm currently working on an update for a pretty major application because the original devs left, and even just over the course of 12 months or so, dozens of new issues arose as usage picked up and more use cases were explored. Software is never static, there's always some to improve, fix, correct, test - this is no different, it's a bit of adaptive maintenance due to a requirement from the OS, and devs were well aware of this months ago.
Man! I hear ya! Good thing it wasn’t all at once.

Actually, some study resource libraries are much much more than $1,000. The Logos app/program has a $7,000 dollar scholar package. I have around 6,000 physical books in my home library for sermon prep and lesson prep (I teach in an international college). An iPad plus study apps have made it to where I can carry most of my research library with me around the world. $1,000 is cheap compared to the benefits of having the books in a moblie form. Plus it’s part of how I make my living. Like buying good tools.
I feel for you, certainly your case is a bit of an outlier (in regards to the price). The development I mentioned above, is for a client with deep pockets, so it's easy for them to adapt.
If the data/resources could be extracted (I'm sure that's easily done), maybe you can put together some interested devs from your organization and build a new app. Make it opensource*, I think given the nature of the app and your situation, you'd have a decent amount of interest and contributors.
(* The app could be opensource, even if the underlying data has some cost associated for licensing)