How to track "Virtual Buckets" savings account in Google Sheets when investments fluctuate?

I’m building a Google Sheet to virtually "bucket" my savings goals across multiple accounts.

I have specific goals (College Fund, Down Payment, Retirement .. etc) that are spread across different account types (RESP, TFSA, HISA, GICs). To manage this, I created a two-tab google sheet, an input tab that i log transactions into ( amount, goal, saving account) and an overview tab that shows columns as goals and rows as accounts with total cell at the end of each column.

The problem is, tracking HISA and GIC balances is easy because they only go up. However, since the TFSA and RESP hold investments, the balances fluctuate. how do i log those ?
do I log negative values every time the market drop ? and if so, how do i decide which goal do I assign the negative values to !!
I'm just curious if somebody else is doing something similar how are they navigating this issue.