Summary:
- There is no written help, other than for scripting
- Online help is limited to videos
- Videos are incomplete
- Videos demonstrate controls with only Japanese labels, but no English subtitles supplied
- There are tooltips for icons
I began by trying to determine what the Chain icon on the piano roll is. That’s the icon that’s to the right of the Pencil icon.
The menu option Misc | Show Help (Online) does not lead to online written documentation, but instead to a Resources page that offers “Downloadable materials for Synthesizer V Studio”.
Those resources are currently:
- Video tutorial series (YouTube, English/Japanese version)
- Video tutorial series [(Bilibili, Chinese version)
- GUI translation files
- Scripting Manual
There appears to be no written user manual.
Choosing Synthesizer V | Synthesizer V Studio (https://dreamtonics.com/synthesizerv) from the menu leads to a page that has a number of issues:
- Despite selecting English as the default language, the page renders in Japanese.
- Changing the language to English brings me back to the Resources page.
- The materials on the page don’t appear until the page scrolls down to that section.
- There is a Support item on that page, but it’s actually better translated as Compatibility.
So apparently the only way to learn how to use Synthesizer V is to watch videos. 
The videos show Synthesizer V with the Japanese interface. The videos have high-level labels, such as Edit Vibrato Properties, but as various sliders are demonstrated, no English subtitles are displayed.
As of yet, I’ve been unable to discover what the Chain icon does. An exploration of the Synthesizer V website leads me to conclude that, if it is documented, it’s not obviously discoverable.
What’s the point of adding features to an application if there’s no obvious way to find what that feature does?
