The eqMC information is telling you what is the MC value you are actually flying with.
Although it might sound strange to you, EqMC is widely used by paragliders, because it represent your current flying parameters, and it allows precise arrival altitude calculations. Read why..
Normally, you set MC and then you follow the relative MC speed to fly; the eqMC works the opposite: it converts your airspeed to MC. This value is averaged over a period of time, which is the same defined by the L/D Average period in System Config menu 5 "Glide Computer". Paragliders are normally using low values, around 15 seconds, while gliders use 90 to 120 seconds; however it is a pilot's choice.
Equivalent MacCready is calculated using the Airspeed value. If you have no airspeed available, then the "estimated" airspeed is used. This estimated airspeed is calculated using ground speed, corrected for the vector wind and air density at your altitude.
If the wind is not correct, the airspeed estimation will be wrong, and so will be also the equivalent MC.
Equivalent MacCready can be used to set automatically MC, in system config menu 5 "Glide computer", Auto MC mode.
AutoMC and Equivalent MC
Using the Equivalent MC as the value to be automatically assigned to MC is possible through System Config menu 5 "Glide Computer" in the Auto MC mode box.
If you are not keen in using MC manually, and flying according to it, then you might consider using this AutoMC option. In fact, gliding calculations and arrival altitudes will be made adopting your current flight speed, instead of the contrary.
In any case, as usual, changing MC manually will exit AutoMC mode and you will be able to adjust it at your convenience.