Both use our IRL Gregorian calendar month names(this comes up in ToP’s side materials too) and as far as I’m able to tell the year lengths are also the same as ours. I’ll make a note that it’s important that Aselia uses a Solar-based calendar system to measure years since the planet has two different moons with two different orbital periods which would make a Lunar-based calendar overly-complicated.
Symphonia never specifies on a calendar system but I would speculate that either it is or is strongly related to the Solar calendar mentioned in ToP. After the worlds are rejoined at least and until after the end of the Ragnarok War when the world’s named was changed from Earth to Aselia when society switched to the Aselian calendar.
Written by Texanona