And your voltage is 230 V L-N?
Your value of 6.9 kW is wrong because the 30 A represents the peak (or d.c.) maximum current, the rms value that is the normal and assumed measure of alternating current will be about 21 A or less, depending on the exact shape of the current waveform. So a little more than 4.8 kW.
Is your oven actually connected across 2 phases, or even 3? That could explain why you see current on two phases.
If you’re confident with the Arduino, why don’t you use 3 × ZMPT101 modules to measure the three phase voltages, and three SCT-013-030 c.t’s to measure the phase currents? You’d need to make up the c.t. interface circuit (see the ‘Learn’ section) but the ZMPT module would connect directly to the ADC input of the Arduino.
The ADS 1115 isn’t a good choice - at a maximum of 860 samples per second, that’s only 17 samples per mains cycle shared between the voltage and current inputs, so about 8 sample pairs. The emonTx (the same processor as the Arduino Uno) with emonLib can do 55 sample pairs per mains cycle.
The MCP3008 would be a better choice, but another user is struggling to get that working with a Raspberry Pi (DIY Current Monitor on Raspberry Pi. My power calculation isn't accurate. Help please?)
I’m not familiar with the ESP32, so I can’t really help. The link to the schematic of the DOIT is 404, so there’s no useful information available to me. The only suggestion I have is, have you calculated the sample rate, and (if you’re using calcIrms( )) the correct number of samples to average over? Because if it’s doing 200 k or 2 M samples per second, you need to average over an absolute minimum of one fiftieth of that (i.e. 40 k or 400 k samples).