With that mic you must also have a device to connect it and your computer running REW. That is more challenging than using a supported USB mic.
Your measurement doesn't specify any calibration files which UI think you could get for mic and make for the device connected to the computer (this one matters less).
When I started using REW, it was with a Dayton mic and TASCAM sound card device. I also had a Beringher mic from an SMS-1 that I tried with the TASCAM. When I saw frequency variance between these, I got UMIK-1 usb mic to make it easier to do measurements.
As example, attached a MDAT file from my initial measurement of LF speaker and a current one. Either measurement will show you that frequency varies much more wildly than your measurement. Without smoothing the upper frequencies vary wildly with ringing from reflections in the room. Your measurement shows variance in bass and lower mid ranges but going higher in frequency it stays in a tight range as though there are not any reflections or the measurement is electrical signal instead of an acoustic one.
The phase in your measurement is presented narrowly and lacks transitions as though it is all one phase. The Impulse pattern is unusual with a peak then 6ms of little movement, then movement you'd expect to see right after the peak. These are not what I've seen doing acoustical measurements. Please be aware that my experience is limited to trying to make sound system better (e.g. I'm an amateur).
I think you need to work on how the gear is set up to get a better acoustical measurement.
Sorry I am unable to be more helpful. Good luck moving forward.
Greg
PS - There are multiple differences in my two measurements. The speakers are the same, but their position, listening position, mics, where signal is introduced are different.
