I used Quickbooks desktop for my Little League Baseball nonprofit. Far cheaper than the cost of time and effort to build from scratch. So what if there are unused features.

Accounting is accounting, doesn't really matter if it is non-profit or business. Possibly Northwind template could be adapted for a non-profit. Really don't see how building queries in Access is "more difficult". And the complication depends on the level of "user-friendly" features designed into GUI.

A large Excel file can become sluggish to the point of non-functional. I also urge you provide file for analysis.

Which "dynamic functions" draw you to Excel?

AFAIK, non-profit does not have "retained earnings" because, well, it is a non-profit. Seems term for a non-profit is "accumulated funds".