I do not think I'm reading a modern reading of "days" into anything. The literal reading says "days."
Any observer will see "days" and the general nature of the story being in terms of days.
It is only theological interpretation that enables you to say anything else about those "days." A straight-forward observation says "days." Likewise, a straight-forward observeration says: Sun, moon, fish, plant, tree, etc.
No, accurate translations read " - the first day" etc. set off from the previous days. If the writer meant 24hr days, he would have made it say so instead of setting the "day" off as period marker and using a word (yom) that has at least 3 literal meanings, including long-ages.