IMP with SingleTact Sensor

I’m not an i2c expert, but I was curious about your post.

Is this the specs you are using for Tact (see i2c section):

Address seems to be 0x04 … you have 0x004. Not sure if that makes any difference.

Read value is 2 bytes (MSB, LSB) as you have specified:
i2c.read(i2cAddress,"\x85",2);

But the PDF shows two registers 132 and 133.
decimal 133 = x85
should you be referencing x84 instead?

Finally, there is an example using an i2c temp sensor:

Not the same thing as your sensor but it might trigger some ideas.