II've tested Lincomatic liquidTW2 library ( https://github.com/lincomatic/LiquidTWI2/ ) with an Adafuit i2c LCD backpack (http://www.adafruit.com/product/292 ). with a bidirectional i2c level translator, since backpack and lcd are 5V.
Unfortunately, it does not works out of the box. However, this can be solved easily by inserting a delay BEFORE using the lcd.begin, an an other delay before sending first string.
I suspect init time was shorted too much in the library, and because C3200 is much more fast than an arduino, fisrts strings where sent before complete lcd init;