It could, but there is some randomness to the logic, the quantities are not just fixed values, so I'd need to know how this is currently implemented - the calculation to determine the quantity of harvested crop itself, which is what currently always returns the minimum harvest value. Without knowing that, any changes would be just a speculation on how the game operates.If the mod incorporated this segment of code (as shown in your linked page) in its then version can't it simply be replaced with the raw data of 1.5.1 to give it the matching values for each crop?
If anyone knows the rules the game uses to determine how many crops will be harvested - Even if it's not code, just a knowledgeable observation of how this system works - I could implement it in code. I know the game, but not deep enough to know these details.
My guess is that the higher your farmer level, the more crops you can get, up to the maxHarvest determined by the crop data, so for example: a level 10 farmer can get from 1 to 3 berries, while a level 5 farmer can get from 1 to 2 - and that maxHarvestIncreasePerFarmingLevel will only show the ratio of increment, but is not used anymore. So the 0 value of maxHarvestIncreasePerFarmingLevel for Coffee beans makes sense in this case, as both minHarvest and maxHarvest are 4 (Checked that during development), so there's no possible increase from Farming Level.
But again, I'm not sure if it's really like this in the base game, any tips will be helpful! I'm listing all the potential fixes and ideas, to work more on it next week.