Here's what I see in clock.xc:
// {{H}} - hour in 12-hour format / часы в 12-часовом формате
// {{AM|PM}} - AM/PM / AM/PM
// Macros formatting allowed, for example: {{AM?a.m.|p.m.}}
//
// Clock format.
// Формат часов.
"format": "<textformat tabstops='[105,105]' leading='-39'><font face='$FieldFont'><font size='36' color='#f3c57a'><b> {{h%02d}}:{{m%02d}}</b> {{AM?a.m.|p.m.}} </font><tab><font size='15' color='#e3dfc6'><b>{{D%02d}}.{{M%02d}}. {{Y}}\n<tab>{{WW}}</b></font></font></textformat>",
It looks like "H" should be used for 12-hour format, not "h". I made the change manually and now it works just fine.