I think that is too high standard.
To avoid falsehoods is a reasonable standard.
For example, the Norse mythos.
Deities & Demigods makes many false statements.
"Balder (God of Beauty)"
• Baldr is a vættr, an animistic nature being, not a polytheistic god.
• Baldr has nothing to do with being worshiped, nor being worshiped for his ‘beauty’.
• Baldr is daylight. Literal daylight. The same daylight streams thru our windows.
• Daylight is beautiful.
• Daylight reveals truth.
• Daylight brings new life.
• Daylight brings new hope − especially in northerly dark winters.
"Valkyries. These warrior maidens ride pegasi."
• Since when has any Norse text ever mentioned the word ‘pesasi’? Certainly not in relation to the valkyrjur.
"Thor. Chaotic Good."
• Þórr literally is social order. If anything he is Lawful Neutral.
• Norwegian Norse view him as rescuing humans, so at least here, Lawful Good (with hints of Paladin smiting) seems fair.
"Odin. Neutral Good."
• Óðinn is a Danish thing, Freyr is a Swedish thing, and Þórr is a Norwegian thing.
• In the Norwegian version of Óðinn, he is treacherous, probably Evil.
• Óðinn is literally cosmic order, astronomical cycles, seasonal cycles, etcetera.
• Probably Lawful Neutral, but again too treacherous. Neutral at best, probably Neutral Evil.
"Norns. three."
• There are many nornir.
• The three jǫtnar nornir are more about the fate of the cosmos, like when Ragnarǫk happens.
• But when it comes to the lives of human individuals, the alfar nornir are way more important.
• The jǫtnar Nornir are called Neutral, and probably fair enough, cruel inscrutable fate
• but a Norse tradition views these Nornir dooming the æsir in Ragnarǫk in order to protect humanity from them
Frey (sunshine and the elves)
• ok but peripheral
• Freyr is specifically the natural phenomenon of sex
• In addition to sexuality, Freyr connotes wealth (fertility) and peace (good relationships)
And so on. I can continue at length about the many falsifications in the Deities & Demigods.
It isnt just that the Deities & Demigods is wrong, it is the book is wrong about some of the most central concepts that matter to these cultures. It is misappropriation.
I am just giving examples pertaining to Norse spiritual heritages.
At the same time, I am familiar with many religions because of my anthropology, and because of friends who adhere to those religions.
The Deities & Demigods is false about other peoples sacred beliefs.