Sometimes those cross reference chart suggestions are questionable at best, they may physically fit and run but they aren't a close equivalent in terms of heat range and other important considerations.
What people fail to understand is there is no "Standard" for individual spark plugs.
As such some plugs have a wide temperature range and some have a very narrow range.
The temperature ranges themselves are not linear.
So there is a lot of overlap and very few plugs are a direct & exact replacement for any other plug.
A lot of plugs are more or less obsolete.
Those for cast iron iron heads running post WW II pool petrol can mostly be replaced with a single plug.
Similarly all the tight range plugs required for the highly tuned 10:1 to 12:1 leaded engines of the 60's & 70's are fairly well obsolete as well.
Mower engines are very low tech and fairly modest compression so the only real thing to worry about is the resistance required for the electronic ignitions to work properly.
Most Champions cover a heat range of 3 to 4 NGK's
The closest direct replacement NGK for the original specified Champions in my iron headed side valve engine is a B 8 HS
It runs best on a BP 5 HS . The B 8's carbon up and foul when idleing for prolonged periods due to the nature of modern fuels which are nothing like petrol.