That is absolutely not the case. The scale for the old SAT was based on an 2400 point maximum and the new a 1600 point maximum, however an old 1800 does not equate to a new 1200. I am not sure how you made your calculations, but I read your earlier post to mean that your daughter increased the equivalent of 350 points when adjusting the new score to the old score. That is (for example) if she scored an 1800 on the old SAT the conversation of her new score would equate to a 2150. That is a huge (and unlikely) jump and indicates that you have not applied the proper conversion tools.
The raw scores on the new SAT are estimated to be, on average, higher than on the old. For example, a 600 on the old math might be the same as a 650 on the new math.
Yesterday, College Board released Concordance Tables which can estimate old versus new/new versus old.
https://research.collegeboard.org/programs/sat/data/concordance