How do I calculate the power consumption for a 3 phase motor?

Your calculations are almost correct.

The startup current can be neglected, since it should only last less than a few seconds.

You should use a power factor, which is dependent on the motor specifications and its load level.  Typical values would be about 0.75 - 0.85 for this small motor.

You don't mention if the voltage is measured line-to-neutral, but this is a reasonable assumption in the U.S.

Your calculation of daily energy consumption sounds about right for a small motor (about 2.5 hp) running for only about a half hour per day.

for three phase:
P=3^½* E * I * cos theta, usually p.f.=0.8
use the highest amp reading= 4.90 amps
P=1.732* 127 * 4.90 *0.8
 =862.25 watts ÷ 1000= 0.862 kw.
power consumption per day at 19/60 hours= 0.3166 hours
so kwhr per day= 0.862* 0.3166 = 0.2729 kwhrs

 if i'm not mistaken the horsepower rating of the motor is ½ HP.

The 127 volt reading could be a line to neutral voltage for a motor operating at 220 volt line to line. In the USA, there are three phase systems rated at 208 volts and 240 volts. 220 volts would be within the normal range for either.

Your calculation would be correct for a line-to-neutral voltage measurement except that you should have multiplied by the power factor. The power factor is likely 0.8 or less. At 0.8 pf, your calculation would give 1407 watts. One horsepower would be 746 watts at 100% efficiency. At 90% efficiency, 1407 watts would be 1.7 horsepower.

If you use the 220 v line-to-line voltage, 4.6 a average current per phase, and 0.8 pf the calculation is W = V x A X sqrt3 x pf = 220 x 4.6 x 1.73 x 0.8 = 1401 watts.

The power factor for full load operation may be on the motor's nameplate. If the motor is operating considerably below rated load, the power factor could be much lower.