Sometimes dodging is harder and less safe in these modes than actually engaging the enemies. Most speedrunners don't kill anything because even a single zombie may take a long time, but if you just want to complete the run, you can take your sweet time with your positioning and the enemies - just be mindful of your resources, of course. Try to memorize the encounters and not rush too much and you should be fine for 4th Survivor/Tofu/Ghost Survivors.
Also, Hardcore is indeed hard, but not THAT much. It's basically the same thing, you'll just need to be more careful with saves (limited), inventory management (less slot expansions), damage taken (higher than standard) and also know that enemies will take more time and effort to kill (more HP). If you got S on Standard, I believe you're more than prepared for a Hardcore run tbh. For a S+ rank you might need some practice/trial and error, but for just completing a Hardcore run with any rank you should be ok.
