Wow, thanks for that detailed review, and thank you for taking your time with our game!
Regarding placing weights on both sides - seems like it is a big misunderstanding for a lot of players, so it's high on our list of priorities to make player to understand that early on.
Fake weights might or might not actually be fake!~ They were a feature we wanted added, but unfortunately had to cut out from the game jam version of the game due to time limitations. Undercover cops might have also been a feature attached to these fake weights, so that you wouldn't overuse them!
Buy/sell text is shown ingame for more meticulous calculation during the game, but it wasn't put on the buy screen due to space limitation of our buttons and to not overload the player with more info (that casual player usually won't think about too hard). Spices themselves also come at different amounts, which is also an important stat when thinking about their profit. I believe this system should be reworked a bit to make it more clear for the player.
Angry customers are also an idea we had that wasn't implemented due to time constraints. Ideally, different customers should have different tips, buying spice types and their patience.
Thank you for these suggestions, we will be taking them into account!