I think when we generally talk about whether something is "repairable" we're referring to the ease of repair, which translate to the repair being affordable and makes economical sense so people actually do it vs buying a replacement.
To me, "repairable" means "capable of being repaired in a practical way". I'll also grant you the unstated "at a reasonable price", which for me, having a cheapskate nature, I've always found the repair parts (batteries, screens, and buttons) to be extremely reasonable in price.
For people who don't want to DIY it, most every mall has a kiosk that will do it for 2-3x what I paid, but still <15% of the price of a new iPhone.
"If it can be repaired in a practical way, it's repairable" seems more resilient and probably no more a judgment call than the design questions above.