In OSRM.Locale.en.js:
"DIRECTION_6":"Turn slight left[ on %s]",// => should be DIRECTION_8
"DIRECTION_7":"Turn left[ on %s]",
"DIRECTION_8":"Turn sharp left[ on %s]", //=> should be DIRECTION_6

As this mistake was introduced in English version, localizations made the same error.

Same mistake is done on direction icons.