I configure xcompose and faced with strange behavior.
add a ~/.XCompose string
<Multi_key> <Cyrillic_de>: "1" then “everything works”: after pressing (and releasing) the compose key followed by entering the letter d, the character 1 is entered.
and if you replace the line with this (one character added to the wildcard string):
<Multi_key> <Cyrillic_de>: "11" then after pressing the compose key and then d nothing is entered, but a signal is heard, as if there is no such compose- sequence.