Are there any alternatives to "We don't know who made this Buddhist image."

 That's an excellent question, as it's a common situation in art history and museum contexts. Here are some alternatives, from academic to more general, that you could use to describe a Buddhist image with an unknown creator:

Academic/Formal Alternatives

• "The artist of this Buddhist image is unknown." (A direct and precise statement)

• "The creator of this Buddhist sculpture is anonymous." (Uses the specific term "anonymous" for an unknown author/artist)

• "This piece is by an anonymous master." (Used when the work is clearly of high quality but the artist's name is lost to history)

• "This Buddhist image is of unknown authorship." (More technical, often used in art catalogs)

• "The sculptor's identity has been lost to history." (Adds a touch of historical context and mystery)

• "This image is attributed to an unknown artist of the [period/region] school." (Places the work within a stylistic context, even if the individual artist isn't known)

• "The artist is unrecorded." (A simple and factual statement)

General/Descriptive Alternatives

• "The person who made this is not known." (Clear and easy to understand)

• "We don't know who the artist was." (A very common and straightforward way to say it)

• "This statue's origins are a mystery." (A more evocative and informal option)

Specific Contexts

• In Japan, for example, many older Buddhist images are often referred to as being "by an anonymous sculptor of the Nara period" or "by an anonymous workshop." This acknowledges that a group of artists likely worked on it, even if a single name is not attached.

Choosing the right alternative depends on your audience. For a general audience, a phrase like "We don't know who the artist was" is perfect. For a more academic or museum setting, "by an anonymous master" or "of unknown authorship" would be more appropriate.