I’d keep the first version in Google Sheets if the goal is fast review and easy auditability.
The main thing I’d add is a clearer “why this lead got this score” field beside HOT/WARM/COLD. If a human approver can see the source, score reason, suggested next step, and email draft in one row, the workflow becomes much easier to trust.
A dedicated dashboard makes sense later, but only after you know which approval fields people actually use.