Where was it revealed that Jubstacheit is an A.I?

Question

So I read this question, where it says:

the only exception being Jubstacheit, who is supposed to be an A.I. controlling an array of humanoid golem bodies.

I've never read this before, so I looked it up on Jubstacheit's Wikia page, where it says:

Jubastacheit is an artificial intelligence made to control the Einzbern Castle, Golem Jubstacheit (ゴーレム・ユーブスタクハイト, Gōremu Yūbusutakuhaito?). It manufactures humanoid golem terminals, and Acht is the eighth generation.

However, this was not the case as on June 11, 2015, the same paragraph said:

Declared the eighth head of the Einzbern family, Jubstacheit was not around during Justeaze Lizrich von Einzbern's era, but kept himself alive for nearly two centuries by continuously prolonging his life.

This part started to change on January 13, 2016, and this new information had not been cited, as the only reference on the page is the Fate/Zero Season 1 Boxset - Drama CD 1, which has been there for quite some time.

So I am wondering, what Nasuverse title/material book says that Jubstacheit is an A.I?

Answer 1

According to Japanese fan-wiki, the Fate/Zero Blu-ray Disc Box I's Drama CD 1 only tells a story in which Jubstacheit has a major appearance.

長い間殆ど設定上の人物に近かったが、『Fate/Zero』Blu-ray Disc Boxの特典ドラマCDにて、ようやく出番らしい出番が与えられた。

After a long period in which his character has been described as such, he finally appeared in Fate/Zero Blu-ray Disc Box special Drama CD.

However, according to a summary of 2channel posts (in Japanese), his true-form is explained on Fate/stay night [Unlimited Blade Works] Blu-ray Disc Box II.

Fate/stay night[UBW]Blu-ray DiscBoxⅡにて明らかになるアハト翁の正体とアインツベルンの成り立ちとは【ネタバレ注意】
Old-man Acht's true-form and Einzbern' rising becomes clear in Fate/stay night[UBW]Blu-ray DiscBoxⅡ (Spoiler alert)

9: ＵＢＷのＢＯＸが密林から届いたで。 アインツベルンとアハト翁の正体とかかなり意外だった
9: The UBW Box from mitsurin (jungle/dense forest, net slang for Amazon) has arrived. Einzbern and Old-man Acht's true-form was quite unexpected.

17: アハト翁はアインツベルンの城の中枢制御用に作られた人工知能ゴーレム・ユーブスタクハイトの8代目人型端末。[...]
17: Old-man Acht is the 8th-generation humanoid-form terminal of Golem Jubstacheit, an artificial intelligence in charge of Einzbern Castle's operation. [...]