ICAO Annex 13 defines what is and isn't classified as an accident.
There is very little scope for "interpretation".
Well, that's not completely true. Many organizations have their own definitions of what is / isn't classified as an accident, although ICAO definitions tend to be used as a starting point.
Most notably, in the airline industry much of our safety statistics are based on IATA definitions, which are more restrictive than the ICAO definitions. I.e., many events categorized as accidents by ICAO are excluded from IATA's definition.
Hence ICAO accident statistics can't be compared directly with IATA statistics. The Global Safety Information Exchange (GSIE) was created in part to facilitate exchange of data between the two organizations.
Similarly many researchers (e.g., from Flight Safety Foundation) may use their own modifications of the basic ICAO definitions depending on the study -- usually because the ICAO statistics tend to be over-broad.
It's perfectly fine for guadaMB to include / exclude data for specific purposes as long as it's clear to everyone what were the intentions behind them.