I have a question for you: Does this macron act like a typical vowel sign, like the stroke in ଆ/ା , or does it act like a secondary modifier that combines to other vowel letters and vowel signs also (say, does it combine to ଆ/ା, ଇ/ି, ଉ/ୁ, ଏ/େ…)?
If you would prefer to send me a direct message with your email address we could continue the discussion privately. That way you might be able to send me more samples of this character in use.