Whats funny is it say pumpkins have a value of 2 which means you (should) need half the mentioned quantity of the cabbage (value 1) which would be 4 pumpkins yet doesn't work. I tried 6 (i forget what skill level) and it didn't work. 8 pumpkins did. So unless I'm interpreting the recipe wrong and you actually need twice the amount of pumpkins the substitute values are wrong.
You're interpreting this correctly. However, please keep in mind that the substitution data is not stored in the game client. It came from the server side data leak, which happened back in 2021. That's the best we have at the moment. So of course the ratios could be changed since that time. It's better to consult the most recent user comments.
I think there was also a mention of there was a possibility of failure with those substitutions, with higher Life Skill levels helping with the percentage. I have had a few recipes that would work several times, then fail. I haven't tried any since they combined the Skill Levels for the entire family.