Annoyingly, pasting the positions into XBoard and making the moves by hand, they are accepted. However, in the second position it interprets "g7e7" as an intention to castle with the next pawn, which is quite obviously wrong and may be the underlying reason for the problem in the other positions.Evert wrote: Other than those:
In this position, dr1b1k4/10/pp3pq2p/2pD2p3/3pp5/1P8/4P1BP2/PP1P2P1RP/6K2d/1RQ7 b - 2 24, XBoard refuses the move "f7f5", which is legal.
In this position, 10/1B8/1p1p2qp1p/6l2r/4pb1B2/1P5P1P/8P1/P1P2PQ3/10/D9 b - 6 36, it refuses the move "g7e7", which is again legal.
[...]
EDIT: one more, 6q3/3k6/p2p3d2/p1p7/10/1P1P1uD3/9P/10/6u2Q/10 b - 9 70, the move h7b1 is refused.
EDIT: moving Q to its normal position in the pieceToChar table and leaving the king position blank (.) indeed allows playing games without spurious illegal move claims. The downside is that XBoard puts spurious mate markers (#) on all moves.