Is There a Fire Emblem Game Missing From the Timeline?

Is there supposed to be a Fire Emblem game between Three Houses and Engage? Fire Emblem games, dating back to the DS even, has been internally codenamed iron, as a reference to FE, the symbol for the element, followed by the entry number. For example, New Mystery was codenamed iron12, Awakening was iron14, fates was iron15, Echoes was iron16, and Three Houses was iron17. iron13 is oddly missing, but it may have existed as another game at some point. Though, that's not the only instance of a missing codename.

One would expect Fire Emblem Engage to be codenamed iron18, but mysteriously, it is actually iron19. Fire Emblem Warriors was never treated with the iron codename, and Three Hopes didn't have it either, but instead, codename Seasons.

To quote Engage's TCRF page
"Many of the files refer that the internal name for this game is Iron19, this refers the game as the 19th main Fire Emblem game even though it was officially released as the 18th main game, however, there is a refence to Iron18 in data.unity3d possibly referring to a separate mainline Fire Emblem title in development or an older internal name for the game."

Even more surprising, is that there is, in fact, a mention of iron18 within Fire Emblem Engage in spite of the Engage being referred to as iron19. So, what's going on? Is there an iron18 for real or nah? Its completely reasonable to suspect that iron18 was just an artifact of Engage's older internal naming conventions...but what if it wasn't? Is this possible? For the sake of fun speculation...
---
TCRF page https://tcrf.net/Fire_Emblem_Engage#Internal_Project_Name
Original leak https://www.reddit.com/r/fireemblem/comments/vcgblq/the_new_mainline_fire_emblem_leak_is_real/
Engage's production https://www.reddit.com/r/fireemblem/comments/10qluo4/about_fire_emblem_engages_production_and/
Iron# Thread https://forums.serenesforest.net/index.php?/topic/87291-the-official-three-houses-site-has-launched/page/3/#comment-5439637
Relevant Tweets:
https://mobile.twitter.com/DeathChaos25/status/1617204558597623813
https://mobile.twitter.com/Aveyn_Knight/status/1616491786112729092
https://twitter.com/VOOK64/status/1617867735945605120
---
Subscribe: https://goo.gl/1xHJzR
WATCH ME LIVE: @faerghaststreams
Patreon: https://www.patreon.com/GhastPatreon
Twitter: https://twitter.com/ghaaast
Instagram: https://www.instagram.com/kdmey776

Видео Is There a Fire Emblem Game Missing From the Timeline? канала Faerghast