Since significant specials don't have order numbers like regular episodes, they need to be at least day apart for "Next Ep." link to jump from one to the next. However, when there are multiple significant specials aired on the same day, they will all simply be skipped. Only first will show on "Next Ep." and only last will show in "Previous Ep.".
15 Dec 12, 2020 December 12, 1941
S Dec 12, 2020 War Against Humanity: December 1941 Pt. 1
S Dec 8, 2020 December 7, 1941: Pearl Harbor Minute by Minute in Real Time - Part 10, 10:40am
S Dec 8, 2020 December 7, 1941: Pearl Harbor Minute by Minute in Real Time - Part 9, 10:10am
S Dec 8, 2020 December 7, 1941: Pearl Harbor Minute by Minute in Real Time - Part 8, 9:40am
S Dec 8, 2020 December 7, 1941: Pearl Harbor Minute by Minute in Real Time - Part 7, 9:10am
S Dec 8, 2020 December 7, 1941: Pearl Harbor Minute by Minute in Real Time - Part 6, 8:40am
S Dec 8, 2020 December 7, 1941: Pearl Harbor Minute by Minute in Real Time - Part 5, 8:10am
S Dec 8, 2020 December 7, 1941: Pearl Harbor Minute by Minute in Real Time - Part 4, 7:40am
S Dec 8, 2020 December 7, 1941: Pearl Harbor Minute by Minute in Real Time - Part 3, 7:10am
S Dec 8, 2020 December 7, 1941: Pearl Harbor Minute by Minute in Real Time - Part 2, 6:40am
S Dec 8, 2020 December 7, 1941: Pearl Harbor Minute by Minute in Real Time - Part 1, 6:10am
14 Dec 5, 2020 December 5, 1941
Here's a list where you can test this. When you go from bottom one (episode 14) it'll show part 1 special but will skip the remaining 9 aired in the same day.
In the opposite direction it will show part 10 but skip bottom 9 that aired the same day.
Not sure how you can fix that without adding ordering numbers to significant specials as well. Or having time (not just date) when it aired.
Perhaps this is not so common with two or more significant specials to be aired during the same day, and probably isn't that big of a deal, but you can put it on to-do list if and when you come up with how to fix this ;))
Cheers!