Re: jaññā

Some observations:

I had a brief look at how the verb "jañña" is formed from the perspective of
traditional Pali grammar, especially that of Kaccāyana with the help of its
commentary, the Nyāsa (Mmd). There are also parallel rules given in the
Saddanīti and Moggallāna.

According to Mmd ad Kacc 470 (Burmese numbering), jaññā is made up of two
substitutes (ādesa-s): jaṃ (for √ñā) and ñā (for eyya. opt. 3rd pers.
sing.). It goes into some detail on how the word is formed, mostly through
quoting a number of other rules from Kaccāyana. Similarly, it also explains
"jāniyā" (another optional optative form, 3rd pers. sing).

I do not find anything about jaññā being also used for the 2nd pers. sing.
or the 3rd pers. plural optative which could easily have been included in
Kacc 508.

Best wishes,

Jim