I made a half batch of the cookies and incorporated 5 ingredient modifications along the way.
1) Instead of using granulated sugar, I used fine sugar. I usually use halve the weight of the granulated sugar to find out how much fine sugar to use in a recipe. In this case, I ended up using 41g of fine sugar.
2) I used a key lime instead of lemon juice. Its purpose in this recipe was to react with the baking soda. The cookie should not end up tasting sour.
3) I used salted butter instead of unsalted butter and omitted the salt in the recipe.
4) I omitted the pinch of cinnamon. Just purely because my family does not like the spicy taste it brings.
5) I swapped out the walnuts for an equal weight for pumpkin seeds since that was what I had on hand.
I would not suggest swapping out brown sugar for white sugar. Although I have not tried it myself, I suspect it would make the cookies more crisp and less soft. Since brown sugar is acidic, it also plays a part in reacting with the baking soda and helps the cookie spread. The people from BuzzFeed and SeriousEats have written articles regarding the effects of swapping brown and white sugar in chocolate chip cookies. You may like to read them first before deciding whether to go ahead with changing the ratio of brown sugar to white sugar in the recipe.