Neither of those acids should have systemic toxicity. You’d need a lot of phosphate to get sick, and it is not absorbed very well in the first place (and just leads to diarrhea). Usually it’s for neutralization more than anything.

On the point of methanol: the treatment with ethanol is both to give much more ethanol than you have serum methanol and to rely on ethanol being a better binder. Methanol itself isn’t what’s toxic, it’s the fact that alcohol dehydrogenase metabolizes it into toxic formaldehyde much faster than your body is able to clear it.