It is curious that a supposedly all-powerful and all-knowing god chose to phrase his message to humanity in idioms that, if translated into other languages, make his message look ridiculous.
How is that 'curious'? God didn't create the English language, humans did - long after the Quran was written. Any 'ridiculous' looking translations are on us, not God.
The translations 'all-powerful' and 'all-knowing' are suspect too. It would be more correct to say
most powerful and
greatest knowing. Neither implies that God can do impossible things or know things that can't be known. Quantum mechanics says it's impossible to know everything precisely. In the Bible it says God gave Man free will, so He can't always know what we will do, nor can He force us to do something like eg. translate a word the way
He wants.
The word 'set' comes from the
Proto-Indo-European word 'sed' - to sit, be seated, or lay down in a resting place.
The word 'set' implies a place that the Sun sits in a seat or resting place when it goes down. That's silly, but some ancients believed that's what happened. The ancient Egyptians believed that at night it traveled through the underworld in a boat, to pop out the other side and rise in the East. They obviously didn't think the Earth was round and the Sun orbited it.
'Sinking' is more accurate, as it implies the Sun continues to move steadily after going down behind the horizon. it's going down, but not to a resting place. This suggests that it orbits the Earth, which is correct from a geocentric reference point.
Quran verse 21:33 says "...the sun and the moon; all (the celestial bodies) swim along, each in its
rounded course". No mention of 'setting' ie. being set down, sitting, or going to a resting place.
In ~820AD
al-Biruni - a Muslim - measured the radius of the Earth to between 2% and 20% accuracy (depending on which measure you use for a cubit), by observing the apparent height of a mountain in different places. He explained the phases of the Moon being due to its position relative to the Sun, which obviously means the Sun is always in the sky even after 'setting'. He argued that the Earth rotated and that elliptical orbits were possible because celestial bodies moved in a vacuum, not fixed to spheres as Aristotle claimed.
'Curiously', Al-Biruni was apparently not sanctioned or persecuted by the church for his scientific theories. It's almost like Islam was more receptive to science than Christianity was.