Which parameters are suitable for aci_hal_set_tx_power_level with SPBTLE-RF ?

I know this is probably too late for you, but I was searching for the same thing and managed to find the following info inST document UM2295:

/* MACROS for Power Level definitions */
#define POWER_LEVEL_LOW 0
#define TX_POWER_LEVEL_MINUS_18DBM 0 // = -18 dBm,
#define TX_POWER_LEVEL_MINUS_15DBM 1 // = -15 dBm,
#define TX_POWER_LEVEL_MINUS_12DBM 2 // = -12 dBm,
#define TX_POWER_LEVEL_MINUS_9DBM 3 // = -9 dBm,
#define TX_POWER_LEVEL_MINUS_6DBM 4 // = -6 dBm,
#define TX_POWER_LEVEL_MINUS_2DBM 5 // = -2 dBm,
#define TX_POWER_LEVEL_0DBM 6 // = 0 dBm,
#define TX_POWER_LEVEL_PLUS_5DBM 7 // = +5 dBm.
#define POWER_LEVEL_HIGH 1
#define TX_POWER_LEVEL_MINUS_14DBM 0 // = -14 dBm,
#define TX_POWER_LEVEL_MINUS_11DBM 1 // = -11 dBm,
#define TX_POWER_LEVEL_MINUS_8DBM 2 // = -8 dBm,
#define TX_POWER_LEVEL_MINUS_5DBM 3 // = -5 dBm,
#define TX_POWER_LEVEL_PLUS_2DBM 5 // = +2 dBm,
#define TX_POWER_LEVEL_PLUS_4DBM 6 // = +4 dBm,
#define TX_POWER_LEVEL_PLUS_8DBM 7 // = +8 dBm�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?

So callingaci_hal_set_tx_power_level(1, 7); will set the output power to +8dBm.

aci_hal_set_tx_power_level(0,4); will set the output power to -6dBm.

I believe maximum power isthe default power on state...