Question

If someone were to PH improperly due to faulty equipment would the nutrients that were unable to be taken up by the plant due to PH off-balance remain in the soil? Maybe dumb question but I'm curious to know if the nutrients were to remain, would the plant uptake them once the proper PH is achieved?

Soil has the ability to self buffer, to a point.
If you were to dump say.. 9.0 ph in.. you’d more than likely see issues.
The nutrients left in the medium would cause a salt buildup and you’d most likely get lockout from that.

Soil is very forgiving. My latest grow shows how a horrific hydroponic fuck up can be fixed in soil easily.

While soil can self buffer, it is not a perfect solution.

Eg: Your soil is used to a 6.3 pH and you add in a 9.0 pH solution. You will cause havoc in the soil for awhile but it will eventually sort itself out as long as you only add solutions with a 6.3 pH every watering afterwards.

Highly acidic or highly base solutions will kill off alot of the micro organisms but they will bounce back given time and a balanced pH input.