The climax of Donner's Superman doesn't actually make logical sense.
It doesn't. You can squint at it and torture it a bit, but it still won't.
Why should it? Time travel as a premise introduces contradictions into causality. To use it in a narrative in any intelligent way requires quite a bit of thought and planning.
The script for Superman was a patchwork of drafts, scenes and scenarios contributed by a remarkable number of writers over periods of years, finally beaten into shootable shape and saved by hundreds of creative artists - actors, crew, director, effects people, costumers, etc. - doing their best to create something vivid with some sense of verisimilitude to it all.
That the finished product is beloved after decades rather than falling apart in production and damaging Warners as a studio is a tale of inches and seconds.
It works in parts as a romantic comedy, at times as a Hollywood fantasy ala The Wizard of Oz, sometimes as slapstick. It never gels as an action/adventure.
But they couldn't make it all make sense.