The I2C LCD Component is intended to work with a NXP PCF2119x compatible LCD because the commands used are based on the PCF2119x LCD Controller. You can find the datasheet here: https://www.nxp.com/docs/en/data-sheet/PCF2119X.pdf
Please attach the datasheet of LCD2004a, I couldn't find any with the "a" version. I suggest looking at the datasheet of the controller used by the LCD and the check the commands.
In the I2C-LCD Component, you can use "Custom format" in the General Tab
And then specify the commands if different in the "Custom Commands" tab. Apart from that I don't think any modifications need to be done.