You mentioned taking extra B6, so I think you should use
P5P supplement form.

This topic is still unresolved IMO. You can Google many medical sites including those with real doctors who answer questions.

I found one doctor who just said stop eating things/ supplements with B6 in them. I saw another who said elevated serum B6 comes from dying liver cells.
There are patients claiming levels 10x normal down to twice normal. There are many people over the years asking this question and I have still have not seen definitive answers to this question.

The neuropathy of toxicity (typically from high dose use for long periods of pyridoxine) is more affecting of proprioception and gait.

This is a list from Medscape:
from: Vitamin B6: Reference Range, Interpretation, Collection and Panels

These symptoms are different and more serious than sensory neuropathy.

Sometimes labs make mistakes. Sometimes results are confounding . It is possible that if the specimen is mishandled, the red cells may lyse (burst) and the contents spill into the serum causes false elevations in the tests. Potassium is another nutrient that can give false elevations due to lysed cells.

Red blood cells do convert pyridoxine to P5P so if they burst after drawn from the subject, they would release P5P into the serum.
Conversion of vitamin B6 compounds to active forms in the red blood cell

So I do think that the test may have confounding weaknesses, involving lab errror or mishandling of the sample.
Doctors don't usually respond to elevated B6 levels, but only to the very low results.

Look at your diet. Energy drinks, energy bars, breakfast cereals can contain substantial B6.

At this point the B6 is probably not an issue for you.

Using a methylcobalamin supplement may be useful for you,
since your test was marginally low. 400 is the new cut off for deficiency now.

And I'd consider getting the DNA MTHFR test. It may reveal an error in metabolism for you.