Merlin tries to teleport Galan away, but he notices it and jumps away.

Timeframes will be simple:

Low end=0.1 seconds (peak human reaction as likes of Arthur couldn't notice he moved)

Mid end=0.04=Human's fastest unconscious reaction (he appeared as a blur)

High end=0.005=Faster than eye can see (he just vanished according to Arthur and Merlin)

Distance is larger than Merlin's teleportation range (how far away objects can she affect.

Let's get all the way back to chapter 83.

Merlin teleports Vivian to waterfall and back.

Wyvern nest and back

To mountains>birds>graveyard

And finally, to river>trolls>mountains in ice>a battlefield at night

And back.

Therefore Merlin's teleportation can affect things even in different climates and timezones. I'll focus on later, as it is much easier to quantify.

Elizabeth was taken by Vivian in chapter 61 when the Sun was up.

Both Meliodas' and King's shadows are small, meaning that Sun didn't just rise.

At time of Merlin teleporting Vivian around, shadows are completely below people, meaning it is around Noon.

Based on this, to teleport Vivian where it is night, she would have to teleport her at least to a timezone 3 hours after theirs. In 24 hours, Sun crosses Earth's circumference of 40075 km. This means in an hour, Sun is in position 1669.79166667 km away.

3 hours passed, therefore 1669.79166667*3=5009.375 km

This is minimum range of Merlin's teleportation.

Low end=5009.375/0.1=50093.75 km/s

Mid end=5009.375/0.04=125234.375 km/s

High end=5009.375/0.005=1001875 km/s


Galan's casual speed:

Low end=0.1670948c Relativistic

Mid end=0.4177369c Relativistic

High end=3.341879c FTL

It'll be the best to say high end would be the right choice. Why? because the fact that Merlin and Arthur could not see Galand move at all even in the slightest, and this is two beings that can easily fight MHS+ characters.In this link it also shows merlin couldn't see Galan's own movement or trace and got behind her

I'll be fine with the acceptance of the mid end rather than high end.