actual and expected are swapped in PHP

Curious to know how people go about solving katas like this. I just try and identify some sort of formula through trial and error.
I come up with a guess for a formula and test it with some inputs. I keep repeating until I hit something. This doesn't seem
very efficient but not sure how else to solve problems like this...

Python: returning a wrong string breaks the solver in the random tests ;-)

Unexpected exception raised
Traceback (most recent call last):
  File "/workspace/default/src/codewars-test/codewars_test/test_framework.py", line 111, in wrapper
    func()
  File "tests.py", line 54, in example
    test.assert_equals(you, shift, f'...{Cipher(you).decode(inp)[y:y+100]}... should be in english' )
  File "tests.py", line 11, in __init__
    self.enc_key = str.maketrans(map2+map2.upper(), map1+map1.upper())
ValueError: the first two maketrans arguments must have equal length

How this is not a duplicate of https://www.codewars.com/kata/5befc5d6767c376e28000068 ?

what is appropriate?