I suggest opening a discussion on GitHub https://github.com/openwebwork/pg/issues and deciding what changes should be made to the error messages. Implementing the changes is almost certainly easier than reaching a consensus on the desired behavior.
WeBWorK Main Forum
parserFormulaUpToConstant messages
This forum has a limit to the number of forum postings you can make in a given time period - this is currently set at 10 posting(s) in 1 day