You're right, its a relatively internal parameter, and is currently not documented in the default configuration file. Perhaps it's a good idea to add it to the formal documentation... default value is 10 :
` # Carriage return (\r) support. If zero (0) \r treated as \n and flushed to backend

Carriage return flush support in seconds, flush consecutive line feeds (\r) every X (default: 10) seconds

console_cr_flush_period: 10 `