On second thought, we don't use r_enum_value table in the java code base (except in the Audit package) and would probably prefer to keep it that way for the time being. So we would read transaction type similar to https://github.com/openMF/mifosx/blob/develop/mifosng-provider/src/main/java/org/mifosplatform/portfolio/loanaccount/service/LoanReadPlatformServiceImpl.java#L934

and the "type" property would be added to the json response similar to the one in https://demo.openmf.org/api-docs/apiLive.htm#loans_transaction_retrieve