@Thea_L I’ve implemented Epicor with some small companies, smaller than yours. Part of the issue is Epicor is designed to be Role based offering sophistication in each process. When users wear too many hats, that sophistication adds complexity.
With regards to your bookkeeper, I have empathy. I assume this person is handling AP, AR, collections and other accounting entries. Epicor is a little unforgiving when needing to make corrections.
Make sure they are trained on the tools to make fixes.
Cancellation and Correction invoices are AR’s best friend. Cancellation invoices can also be used to reopen an Invoiced shipment to be corrected and reinvoiced.
Reverse cash receipt is another important tool.
AP now has both tools with the release of 10.2.700.
Add some level of automation to the collections efforts. I like the tool from LockStep, used to be called Cash Collect.
I have worked with a consulting group on these smaller projects, happy to provide a recommendation in PM.