I think the main problem is the way the residual value is handled.
The report will be accurate if it just reverses the qty and cost of all the transactions as it is.
Residual value should be identified at item break even if it is not printed. If the quantity is zero, the cost can be accumulated in a total that could be printed at the end of the report. I don't know how it is done right now but doesn't seem to behave that way.