There is no bug in the rules. Czech Checkers is just a variant played in our country and the rules details had been consulted with top Czech Checkers players.
From Checkers rules:
"If the player has more possibilities to capture opponent's pieces, he/she can select any of them. However, when a king or queen (in variants) can make a jump, the player cannot select a pawn to jump with."
(do skréše) Jak chceš vlitnót do špilo se špilošem, keré bode asi tak dobré jak te, možeš zvolet vežadované rozsah BKR v novy nabidce ke špilo. Potem nikdo, kdo do rozsaho nepasoje, toďto nabidko ani neovidi. (Katechka) (okázat šecke vechetávke)