Overheating issues, possible heater core?

Okay, so my husband last year around this same time replace the timing belt which also came with a new water pump just giving the details of what all is going on then I'll ask the question I apologize I'm a woman so I'll give you as many details so you'll have a good understanding about my certain concern. The car started to overheat which was the first time since we've owned it bought the car in April of 2022. Husband has been working on a slew of electrical issues which stemmed from the window control module and key fob making it go into alarm mode (we drove it for almost 3 weeks in alarm mode then it was fixed or so it seems anyway) and noticed the car was overheating. He then replaced the thermostat, that did not fix overheating issue, then we have filled and filled and let all the bubbles out of the cooling system, still overheating, husband noticed the rubber gasket wasn't sealing properly on the radiator cap so we have replaced that as well, that shouldn't be an issue, noticed a small leak at the top of the radiator, plan on fixing that asap (he works and doesn't trust me to do it which for a girl I am pretty confident in my auto repair skills) either way I'm getting down to the real question here I noticed yesterday sitting in the gas station parking lot that the heater wasn't blowing hot air which it should considering it was definitely hot, I've expressed this as well as he experienced it first hand on the drive to work this morning. Okay, so here is the big question.

If we replace the whole radiator I am concerned that the heater core has gone foul due to running it hotter than usual and that's why the heater isn't blowing hot air when it over heats, problem there is it goes in and out like one time it will, one time it won't usually I'm assuming when the water needs to be filled up and it's starting to overheat. If we replace the radiator will the heater core be okay? Or should we replace both?