Final Fantasy III is a game for the Famicom/NES that never saw release outside of Japan in it’s original form. In 2006, Square Enix remade the game for the Nintendo DS, which was the first time players worldwide were able to experience some form of this game.
This specific translation is actually a ‘do-over’ from a previous attempt in 2016.
Although previous fan-translations of this game exist, they were made before Square’s DS remake. As such, in 2016 Chaos Rush wanted to make a new translation-hack of the original Final Fantasy III for Famicom/NES that aimed to port the script used in the DS remake (when applicable, because the remake alters certain story elements) while retranslating from scratch any parts that were altered in the remake, with the end goal being an English-language version of the original Final Fantasy III with the canon names for characters, spells, items and such. While this initial project was completed, it had its issues: In order to fit the script, Chaos Rush expanded the ROM to 1mb while using a patch that converted the game to use the MMC5 mapper, thinking that there wouldn’t be any issues that stem from it by doing so. Several users pointed out that the RAM configuration used in Final Fantasy III would not have been compatible with the MMC5 mapper to begin with. In addition to that, there were several bugs and crashes that stemmed from the MMC5 mapper conversion, and certain emulators did not support the hack at all. Several users requested that the project be redone in order to keep the 512kb ROM size of the original game and look into ways to compress the script, so that users can finally have a hardware-compatible version of the original Final Fantasy III in English that uses the canon terminology.
With that said, in 2019 Chaos Rush produced a new version of the translation that keeps the game’s original ROM size and mapper configuration. In order to fit the script into the game’s limited space for text, the script had to be redone from the 2016 version, thus a new script was produced that words things as minimally as possible while implementing DTE compression into the game in order to fit as much text as possible within the original ROM size. The new script was produced by comparing the Japanese text from the original Famicom version with the English text from the 2016 translation (which about 75% of was a script port of the DS version), and then coming up with a new line that words things as minimally as possible while getting across the main points expressed in the Japanese script while keeping the “spirit” of the DS script. Thus, it is more or less an abridged version of the script from the 2016 version, but the Japanese text was looked at in both cases. The compressed script takes up 99.97% of the space used by the Japanese version of the game for the text.
Whether you want to call this a translation or an “abridged script port”, either way the end result is an English-language version of Final Fantasy III for the NES that uses the terminology from Square Enix’s remake on the Nintendo DS (and subsequent ports), with a script that provides a similar atmosphere to the remake while also staying true to the original text, all while keeping the same ROM size and mapper configuration as the original game.

https://www.romhacking.net/translations/4760/