Since I'm really not that interested in any mor etreaties with these folks I would edit the second paragraph thusly:
Greetings again Gaul,
We have not received a response to our message that we sent to you on the 27. november. Since then, you have once again moved your scouting warrior within 1 tile of our cultural borders. We consider your moves to be in violation of the treaty we initially agreed to when we established the terms for our current NAP with you, as the treaty stated that we should not move within 1 tile of your cultural borders (which we consider a mutual term).
We are willing to renegotiate the treaty, but we need to to know that we can trust you to honor your word. We desire a peaceful relationship with your team, and we hope you are willing to enter negotiations with us to establish a treaty that both teams are happy with. We are also willing to maintain the current treaty, as long as your team does not break the treaty again. If we renegotiate the treaty, we trust that your team will uphold your end of the treaty, just as we have so far upheld our end of our former treaty.
If we do not hear from you, preferably as soon as possible, we will sadly have to consider our former agreement null and void, with the only exception being the NAP which we will of course honor until it runs out.
Awaiting your reply,
Team Civfanatics