I believe SplPer is in seconds, as it’s also configurable in seconds via the app, and the configuration value stored in the NFC tag is also in seconds.
Not sure about SendPer yet. On the ERS with CO2 sensor that I just checked (a rev E with firmware 2.2.4), the SendPer and several other *Per multipliers are all set to 1. I assume they just /are/ multipliers.