
We see that sample #452 (0x01C3) and further samples up to #512 are actually present in gusdirty.wfb and not that they are much different from #451. Looks like neither of my two previous guesses is true.
Note that WFB samples have numbers from 0x0000 to 0x01FF (not 0x0001 to 0x0200, which is somewhat confusing). Thus, 452 translates into 0x01C3 and not into 0x01C4.
What we also see is that samples starting from #451 (0x01C2) till the very last #512 are not actual samples but empty aliases (while preceding samples before #451 have multisample type). They contain no sample data and there are no difference between them save for the number.

Looking into Fanta GM 8 Mb WFB, we see somewhat similar scheme: samples starting from #424 (0x1A7) are empty aliases, while previous samples are aliases either but not empty.
Thus I have a new guess: Awave Studio writes a sample block length value that differs from actual sample block size when dealing with empty aliases. Look here:

For non-empty alias in Fanta GM we see sample block size (look at the beginning of selected data) is 0x8A, and our hex editor also reports a block size of 0x8A.

But looking at an empty alias, we notice a sample block length of 0x74, while the hex editor still reports 0x8A.
Thus, a WFB loader reads all samples up to the first empty alias, but for the second alias the data read is all screwed due to the incorrect offset, which in its turn is due to a non-relevant sample block size value found in the first empty alias (0x74 instead of 0x8A).
This is yet another guess, but it explains problems with both WFB banks. If I'm right, there are two further guesses:
1) 0x74 is correct value, extra data is wrongfully written.
2) 0x74 is incorrect and should be replaced by actual 0x8A value.
I have to look into it further.
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