Boolean Fields Y/N automatically Converted into true/false during REST Data Export

We are using REST API to do data export to external system for analytics development. The process is that external system sends REST service request to GTM, GTM responds with data (items, parties, licenses and transactions) in csv format. The csv files generated look fine except that MOST Boolean fields in "Y/N" format got somehow converted into "true/false", which is not expected. Please help explain the root cause and we prefer them to stay as "Y/N". SR 4-0001094118 has been created for the same a few days ago, though there is no progress over there yet.

Thanks in advance.