I wrote a script to try it. It's boggling that anyone could do this task in milliseconds.

  import os
  import random

  cols,rows = os.get_terminal_size()
  numchars = cols*rows
  randletter = lambda: chr(random.randrange(ord('A'), ord('Z')+1))
  randnumber = lambda: chr(random.randrange(ord('0'), ord('9')+1))

  letters = []
  placement = random.randrange(numchars)
  for i in range(numchars): letters.append(randnumber()) if i == placement else letters.append(randletter())

  for l in letters: print(l,end='')
  input()

  CEND      = '\33[0m'
  CSELECTED = '\33[7m'

  for i,l in enumerate(letters): print(CSELECTED + l + CEND,end='') if i == placement else print(l,end='')
  input()

I was part of a similar project (as a control) the majority of people who claimed synesthesia did not see any kind of benefit compared to those that didn't.

But a small cadre (I'd have called the people with actual synesthesia) were spectacularly good at some of those tasks.

Another task was doing maths with notes. You got to specify the numbers attached to the sounds.

It'd be like beep-beep-bop and they'd shout 14! Or whatever it was

I would say that math with notes is more likely to be a case of absolute pitch: some people is capable of recognize notes without any reference - no other sense is involved.

As someone who used to have a shade of number color synesthesia, I don't think psychedelics would temporarily induce this in a person. Someone on psychedelics however might find themselves better at this task for different reasons though! My guess is it's depend heavily on the dose and even the substance though...