How are/would newly discovered Suttas (and Sutras) be dealt with, specifically be they of content contradicting -- or even just differing slightly from -- previous material and/or for totally new, original material discovered?
Can example(s) be given on how whatever is done, or not done, happens -- especially any instances kept from the public.
The Pali Sutta Pitaka has multiple editions including the Sri Lankan (PTS), Thai and Burmese (Sixth Council) editions.
Here, I list links to footnotes by the translator (Ven. Thanissaro) commenting on the differences between the three editions for various suttas - SN 42.10, Ud 5.9, Ud 8.6, Ud 3.2, Ud 2.7, Ud 4.8, Ud 1.5, Ud 8.7, Ud 6.10. These footnotes will give you some concrete examples.
The Pali Sutta Pitaka corresponds also to Sanskrit Agamas and the Chinese version of Sanskrit Agamas. There are also the alternative version of the Pali suttas in Sanskrit called sutras.
You can find a very good example in this answer comparing the Pali sutta SN 12.67 with the Sanskrit sutra SF 155 and Chinese Agama SA 288. There's also a scholarly commentary in that answer by Ven. Dr. Analayo.
On this university profile page for Ven. Dr. Analayo, you can find links to more of his scholarly writings, which should give you more examples.
I don't think any such differences are kept hidden from the public. In Buddhism, differences in phrasing is not important, as long as the meaning is unchanged, as evidenced by the following quote from MN 103.
‘The venerable ones agree about the meaning but differ about the phrasing. The venerable ones should know that it is for this reason that there is agreement about the meaning but difference about the phrasing. But the phrasing is a mere trifle. Let the venerable ones not fall into a dispute over a mere trifle.’
The disciples of the Buddha spread the teachings far and wide, touching many different languages and cultures. For example, we have the Pali canon as well as the Chinese canon and many others. Although the correspondence between the different root languages is absolutely amazing, differences do exist. Exploring these differences is an ongoing effort of many scholars.
To catch a glimpse of the discussions that arise, take a look at
As you can see, the work is ongoing and thought provoking. Many other examples can be found.
You ask about "instances kept from the public." That's somewhat of an odd turn of phrase. In fact, the Buddha clearly states:
DN1:1.28.1: There are other principles—deep, hard to see, hard to understand, peaceful, sublime, beyond the scope of reason, subtle, comprehensible to the astute—which the Realized One makes known after realizing them with his own insight. Those who genuinely praise the Realized One would rightly speak of these things.
"Hard to understand" is not the same as "instances kept from the public." But there are indeed cases for privacy.
The academic process itself requires restraint in publication. In general, new papers are "hidden from public view" prior to publication. That privacy is simply a natural process that ensures that their work will be well-received and trusted.
