I was unclear as to whether after the takana of not accepting edim after mincha and the edim would come after mincha or not come at all and the bet din would make the second day RH what would be the status of the first day concerning
2. korban mussaf
...in other words when bet din would declare the second day RH what difference (other than the calendar date) would be between 1st and 2nd day??
Thank you so much, shlomo amar
The Rambam (Hilchos Kidush ha'Chodesh 3:6) says that they would bring the Korban Musaf on the second day if witnesses came after Minchah. R' Chaim Kanievsky in Shekel ha'Kodesh (on the Rambam, Hilchos Kidush ha'Chodesh 5:7) says that they would refrain from doing Melachah and would blow Shofar due to the doubt, but they would Daven a regular Davening and did not make Kidush. However, as he notes in his Biur Halachah there (3:6), what they did and did not do is the subject of much discussion.
All the best,