You're logic looks good - I can't tell if the data is right unless I see the formulas. A couple of notes for you though.
TAR01 is not a system module. Ideally, Account, Product, Product Family, and Country should not be line items in this module. Try using your system modules for that: SYS03 Account>Product Details in particular.
Here's one way you can organize your grid. This one shows 5% for US, yours might be 1%. My recollection is that these percentages will change throughout the course so stay focused on the formulas and test your values using Excel if you must.
I understand you are either asking for help/clarification or replying, but please refrain from posting actual blueprints for Level 3. Asking for help is one thing, getting on a Webex to help is good as well, but posting "solutions" is frowned upon. If you have any questions, please let me know.