No, that's what pkg_rolling-replace is for. Sometimes in long-ago-update situations, you might rm the pkgdb entry while leaving the bits. But you have to figure out what's going on.
What I mean is that if you run "make update" for a package that's a dependency for something else, that other thing will get rebuilt, too.
I don't know what Leopard means as a number and when it stopped being supported by Apple, but I'm guessing it's Really Ancient. I see 10.11 as the oldest macOS that might be expected to mostly work, and probably 12 as the oldest that might be expected to really work. That doesn't mean you aren't welcome to fix things as long as it doesn't make maintenance much harder. Just that I don't expect most people to see it as a problem.
Leopard is 10.5, and is the last Mac OS supported on PowerPC (ignoring the unofficial Snow Leopard builds). Some people want to keep pkgsrc working for PowerPC Macs. I'll have to see if I can put in the time :)
John