Separate eras and products
The defensible approach is to identify the exact application, version, purchase channel, and terms supplied with it. Community practice shows how people work, but it does not prove commercial permission.
Why these tools mattered
Illusion-style tools dramatically reduced the labor required to stage characters and scenes. That accessibility helped define the look and release cadence of an entire branch of indie adult visual novels.
What creators should document
Keep contemporaneous terms, asset provenance, modification notes, and distribution decisions. When the license is unclear, obtain permission or choose a pipeline designed for commercial output.