I can confirm that the magnet pull ability is increasing the spawn rate of electric type pokemon, wheras the wiki suggests it should boost the rate of steel type pokemon, which is also the case in 8.4.2. This can be shown by running /checkspawns both with and without a pokemon with magnet pull on the front of the party, and observing the change in spawn rates of these two types.
Passing this to internal now, thanks!
P.S - removing the security status from this ticket, that is normally reserved for abusable issues like duplication glitches or server crashing methods. This means others can see the ticket and add to the discussion if they have the same problem.