Discord user XoKat remembers a cartoon that supposedly aired in the mid 2000's in the channel "Animania HD". In his words:
"It was a show on the tv channel Animania HD ( i think) it involved 2 siblings boy/girl(maybe like 12/13 years old). It was about time travel and how they went to different times and learned or explored. I just remember one episode had them teleport to Rome i think and they got stuck in a big block of cement in the start. I don't remember much else of the show besides that it was animated and the characters were in like a 2d style"