In MQL5 I was able to get data for the colors by getting the value from the second buffer. The values there range between 0 and 3. This can also be seen in the source code of the file, which is /Indicators/MarketFacilitationIndex.mq5. Otherwise no second buffer is mentioned in the documentation: https://www.mql5.com/en/docs/indicators/ibwmfi
In MQL4 again, there is no word about second buffer: https://docs.mql4.com/indicators/ibwmfi
Worse than that, in MQL4 I don't see how to change the buffer. In MQL4 this is a "mode" argument for the indicator's function. For example, if it's MACD, there is a "mode" argument to select the main or the signal line, look: https://docs.mql4.com/indicators/imacd
Even worse than that, I can't find a custom indicator in /Indicators folder. But if you can find it from somewhere, use it as a custom indicator.