Return confirms an entry and moves the focus to the cell below the first is a series of 'write' tab 'write' tab repetitions.
Tab confirms the entry and moves the focus one cell to the right.
Shift-return and Shift-tab confirm the entry and move the focus one cell up (return) or left (tab).
I've not found documentation for any combination that will leave the insertion point in the same cell, but a test tonight with a new and empty table showed that command-Return will confirm the entry and not move the focus, but does make the insertion point disappear from the cell, leaving the cell selected. Any text of number keystroke then deletes the current content of the cell and places the keyed character as the start of a new entry. I have not checked what other effects, if any that keystroke combination triggers.
Regards,
Barry