LT-13288: Hermit Crab: report unfound phoneme in word

Currently, Hermit Crab just says that the form/word could not be translated
into a phonetic shape. This does not tell the user which character(s) were
the problem.

This fixes that issue by telling the user what the character was.

Change-Id: Ib0bdc8d71472a51b8a15140896adb666016f2ccf