InDesign CS4 and High Sierra- Should I give in and upgrade my Adobe?

If you've avoided Adobe's abusive monopoly CC products so far, keep it up. If possible I would NOT upgrade. I would do what I could to go back to the old install, back up often and wait for the next good thing. I'm running Yosemite and the CS6 design applications work fantastically. I heard about the woes w/ High Sierra and have been watchfully waiting and chosen not to upgrade. Instead I'll let my nice creaky, smooth running system age until the wheels fall off. I run a small studio and was an early adopter of cloud storage (until my files went poof and I got a pittance rebate on my cloud fees) and  Dreamweaver CC. Dreamweaver CC was my baptism by trolls into the hellish new world of Adobe's TERRIBLE customer service for often clunky junk products that phone home constantly while they only need to phone home once every 90 days to confirm you're a legit user. I dropped the broken Dreamweaver CC and reluctantly upgraded to InDesign CC. On the rare occasions I needed support I ALWAYS get mansplained by trolls "Who would ever use that old fashioned process, no one should hire you" (Um client chose the vendor and I have to work w/ vendor) "That is so outdated, you must be stupid, you need to spend more money at Adobe." I recently bought the newest version of Quark and it is stable and their customer service has been great. While offshore like Abobe's, nobody from Quark has called and left me VMs "My name is Prince you have a nice voice, call me back" like some creepy male Adobe CSR did. Quark will also send you invoices, which is important for a business. Adobe used to send me invoices but stopped. Businesses need to support customers. Monopolies don't. Good luck KW.

CS4 is 9 years old, and software doesn't keep running forever (unless you don't upgrade your OS). I'd say you got a good run out of it and it's finally time for an upgrade. Keep in mind that InDesign is now part of the Creative Cloud, so you will be starting a subscription to get the latest version.

The only party that could possibly work out the kinks is Apple. And that simply isn’t going to happen.

I'm sorry to be the one to tell you that no kinks in CS4 will get worked out period. CS4 is now 9 versions old ;-) No resources will be put into that version moving forward. I know it's tough to bite the bullet, but I'd pony up for the Creative Cloud subscription. You'll have far fewer problems! It's actually still on sale for $39.99/month. Even cheaper if you're still a student! Creative Cloud pricing and membership plans | Adobe Creative Cloud