angular-message-format.js currently does not allow you to use custom start and end symbols for interpolation.
You have redefined $interpolate.startSymbol/$interpolate.endSymbol and also
loaded the ngMessageFormat module (provided by angular-message-format.min.js)
while creating your injector.
ngMessageFormat currently does not support redefinition of the
startSymbol/endSymbol used by $interpolate. If this is affecting you, please
file an issue and mention @chirayuk on it. This is intended to be fixed in a
future commit and the github issue will help gauge urgency.
For more information about the MessageFormat syntax in interpolation expressions, please refer to MessageFormat extensions section at Angular i18n MessageFormat