We don't need flavor text. We know that the Realms have existed through multiple editions of the game; if spells were this consistent then they would operate consistently across the different rulesets. They do not, though.

Using Locate Object as an example:

2E Distance: 60 feet per level of spellcaster (so variable between 120 and 1200 feet for levels 2-20)
3E Distance: 400 feet plus 40 feet per level.
4E Distance: ???
5E Distance: Up to 1000 feet.

The spell itself is the same, but the gameplay limitations vary for the purposes of game balance. I sincerely doubt that a spell in-world changed; rather, we set limits to ensure balance in gameplay. We should be distinguishing between rules meant to balance play and in-world realities, here.