How are scriptures preserved when the parampara is lost?

From Pranav Wagh:

1.  the scriptures are apaurusheya, and even today we see that people become devotees by reading the original versions [without interpolations]. How can the apaurusheyatva of the scriptures be preserved while presenting it in the modern genre? (eg. Just like in a grapevine conversation, the original version gets watered down).

2. (a).During some ages when the guru parampara gets lost temporarily.

(b.) Sometimes many deviations arise, like the apasampradayas which arose after the disappearance of the six goswamis .

Do these (a & b) happen because some people who were not qualified tried to present the scriptures (according to what they understood or speculated) to be the current ethos?

3. while presenting the philosophy in a new genre, how to keep the reader firmly rooted and faithful to SP’s books?