MAX11612 to replace ADS1015
According to schematics, the setup you have made is not okay \$V_{REF1}\$ cannot be higher than \$V_{REF2}\$.
below is the typical application. In your case,   

\$V_{REF1}\$ = \$3.3 V\$ and \$V_{REF2}\$ = \$5 V\$   



from datasheet: 


  To support translation, \$V_{REF1}\$ supports 1.2 V to \$V_{REF2}\$- 0.6 V. \$V_{REF2}\$must be
  between VREF1 + 0.6 V to 5.5 V. 



As per datasheet, you can also swap \$V_{REF1}\$and \$V_{REF2}\$. Please use \$V_{REF2}\$ for RPi and \$V_{REF1}\$ for Max11612. This way, the design will be compliant to the datasheet and will be operating as per specification.

You have to provide pullup on both the sides. that is missing in the schematics. 





Founder of I2C has an application note on this:.