In my opinion custom calculation fields would enhance Manager functionality in several areas such as payslip, depreciation schedules, item discount pricing, income tax provisioning (and probably other areas as well). All involve writing calculation results back into Manager, not just displaying a value as is currently supported via liquid programing. Several of these are already ideas:
So I support the concept. However I’m not sure how such functionality is best achieved to deliver sufficient simplicity that users can actually use the function, generality so it supports a sufficient breath of use cases, and robustness so it doesn’t inadvertently crash Manager. I haven’t reviewed how other accounting software supports this functionality.