Touch Diagnosis Routines fails at 4.9V

Hello  

I implement  R_CTSU_Diagnosis() for a project that need  VDE aproval  https://renesas.github.io/fsp/group___c_t_s_u.html#ga45103e8db4a16dfabf3a516ab2da9f26  in RA2E1 microcontroller 

The function works well, when I power microcontroller at 5V,  but if I decrease microcontroller voltage to 4.90V  function reports  FSP_ERR_CTSU_DIAG_OUTPUT_VOLTAGE. Error code 6009.

Error occurs ( I think because made a internal reference measurement  with assumption that  power supply is 5.00V and check values with  limits defined :

#define CTSU_DIAG_TSCAP_RANGE_LOW (1050) 
#define CTSU_DIAG_TSCAP_RANGE_HIGH (1419)

What is the expected value of this measurement at  Vcc 5V? and we can revise defines in order allow wokring with  a microcontroller  Vcc range  between 4,5 and 5V?