Corrected version
2) Usually there is little difference between the date we accept the artwork and the date we are sent the invoice, so this clause mainly emphasizes that our acceptance is a prerequisite for payment. If that is the mutual understanding, we can accept the change. 3) We're not comfortable with the 10-calendar-day limitation. The final decision is made by the boss, who may be away on a business trip, and we'd like some leeway for possible delays. Could we agree to 10 business days, for example? 4) Our legal team hasn’t yet chosen a neutral country for arbitration; I suppose we will cross that bridge when we come to it. :) Also, thank you for explaining the logic behind the deposit. It is helpful to know that we need to secure a spot in your calendar well in advance. I'm afraid nothing is clear on our side yet, and a project may not start until late October or November.
Simple, step-by-step explanation of the main changes
- Changed "dates between the day we accept... and the day we are sent" to "date... and the date we are sent" for clearer and shorter wording.
- Replaced "prerequisite of the payment" with "prerequisite for payment" because "for" fits better here.
- Fixed "that's understanding is between us" to "if that is the mutual understanding" so it sounds correct and polite.
- Removed the duplicate numbering (two items labeled 3); renumbered the arbitration item to 4.
- Changed "10-calendar-day limitation" wording slightly and corrected "agree on 10 business days" to "agree to 10 business days" which is the usual phrase.
- Fixed grammar: "a possible delays" -> "possible delays" and "isn't ready with the choice" -> "hasn't yet chosen" for correct tense and number.
- Replaced "late October- November" with "late October or November" so it is clearer and grammatically correct.
- Made small punctuation fixes (commas, semicolon) and smoothed tone for a polite business message.
If you want a more formal or more casual version, tell me which tone you prefer and I can rewrite it.