need to know if the numbers on a piston is a big deal if the piston numbers are not the same( in the readable?

Question

the pistons are already in the motor but the man has put two of the pistons on each side of the motor with the numbers up and two pistons on each side with the numbers upside down

Answer 1

if you had rings put on,it is no big deal that the numbers are flipped.

Answer 2

Some pistons have a longer skirt on one side to reduce piston slap on the cylinder.
They would be marked with a "notch" tha points toward the front of the engine.

If your pistons do not have that "notch" it's no big deal, they are revesable.

Now, reguarding the numbers, those indicate the weight of the piston so they can be matched with the connecting rod of the apropriate weight.