Spelling and grammar are shaped by two things: social institutions and historical tradition. These can be very conservative. For example, in English we continue to spell words according to traditional spellings (e.g., right, knight) because of social institutions that shape and define spelling. Of course, spelling can and does change over time. For example, the original 1611 edition of the King James Bible has the following: “And the earth was without forme, and voyd, and darkenesse was vpon the face of the deepe: and the Spirit of God mooued vpon the face of the waters” (Genesis 1:2).
Changes in spelling are usually associated with major changes in the social institutions where writing is taught. In ancient Judah, such changes could have taken place in a variety of periods, including the beginnings of the state, the fall of the kingdom of Israel, the social reforms of King Josiah, and the Babylonian exile.
Another important thing to understand is that spelling was taught primarily by practicing vocabulary lists, not by memorizing rules (e.g., “i before e, except after c …”). For example, the Hebrew word for “fortress/city” was originally spelled without the letter yod as ‘r (ער). Eventually, the yod would be included, and the word’s standardized spelling would become ‘îr (עיר).
In some words, especially titles or proper nouns, the standardization process could be quite conservative. And rules were less absolute when spelling a foreign word with a different script in another language. For this reason, we can have many ways to write Hebrew loanwords (with its foreign script) in modern English (e.g., Shabbat, Sabbath, and even Shabbas are all ways of rendering שבﬨ).
This observation is important for the word nabî’ (“prophet”) in Hebrew—as was recently discovered on a seal that may have belonged to Isaiah the prophet. According to 1 Samuel 9:9, nabî’ was a later loanword into Hebrew (probably from Akkadian cuneiform) that replaced the older term ro’eh (“seer”). How do you spell a loanword that comes from a different writing system like cuneiform or hieroglyphs? It is not simple because you have to convert the entire writing system, which can lead to confusion and variation in spelling.