Curious!
this seems to be a side effect of Delphi Compatibility (even though thats off) and Create having a special meaning there. if I add a & before it, it compiles:
method RemObjectsServerTest_SantanderBoletoService_TicketEndpoint_create(...t): RemObjectsServerTest.SantanderBoletoService.createResponse; implements RemObjectsServerTest.SantanderBoletoService.TicketEndpoint.&create;
I hope that suffices as an immediate workaround for you; I will of curse log this to be fixed, as it is a bug…