Steps to get good results from IAST Sanskrit in ABBYY Fine Reader software. Video tutorial, part 1, part 2.
1) https://github.com/gasyoun/Nagari/blob/master/SanskritOCR/IAST.fbt (GitHub sources)
2) ‘-.ABCDEFGHIJKLMNOPRSTUVZabcdefghijklmnoprstuvzçñĀāĒēĪīĻŅŚśŪūḍḥḷṁṃṅṇṛṝṣṭṚṜḺṄÑṬḌṆŚṢḤṀ’
3) https://github.com/gasyoun/Nagari/blob/master/SanskritOCR/SanskritSpellingDictionary.txt
4) Tirupati compilation of common IAST errors in ABBYY
ā ī ū ṛ ṝ ḷ ṅ ñ ṭ ḍ ṇ ś ṣ ḥ ṁ ṃ
Ā Ī Ū Ṛ Ṝ Ḻ Ṅ Ñ Ṭ Ḍ Ṇ Ś Ṣ Ḥ Ṁ
ü ö ä Ä Ü Ö ß