I can only speculate why.
If you decode boba's 4 FLACs and combine them into one large WAV, it'll be 1,395,130,152 bytes.
The original WAV from Belbucus is larger (1,395,131,276) so naturally the CRC-32 won't match.
FLAC doesn't preserve the extra RIFF chunks that were present in the original WAV's non-canonical header.
However no PCM samples are lost. The "fingerprint" will match the one in my quote.
The fingerprint is the MD5 of the WAV's payload only (i.e. PCM samples stored within the WAV) and doesn't include the WAV file's header.
[Contrast the CRC-32 in my quote which is for the entire WAV file including header and extra RIFF chunks.]