These 'reversed' tone letters are used to indicate tone sandhi. For example, ˧꜒ after a word or syllable indicates that it has a mid tone in isolation, but a high tone in the current environment.
When this letter occurs in ligature with other tone letters, they together indicate the pitch contour of the tone. For example, ꜒ means a level high tone, and ꜒꜖꜕ means one that begins high, goes low and ends mid-low.
Tone letter on Wikipedia.Wikipedia 