I Tried to reproduce.
Mapped a Widget to RES H in CS-80.
Saved a CS-80 GP Preset.
Changed the preset via the CS-80 inbuilt menu and then loaded the save GP Preset.
The widget reflects the plugin parameter value.
Change the widget and load the GP Preset (which is already loaded), the widget does not reflect the correct plugin parameter value.
I just tried again with the HaNon organ from Lostin70s, which worked pefectly - then i tried again with the OP-Xa from Arturia which first seemed to work with “ignore variations” OFF, but when i switched “ignore variations” to ON this didn’t work anymore.
So the first try with “working” widgets seemed to be caused rather by the stored widget state in the variation than by the call of the corresponding GP-Preset.
While the Arturia plugin then didn’t work with previously saved GP-Presets (no updating of the widget’s states), the widgets did change on selecting presets from the plugin’s internal preset list.
And it made no diffrence wether the GP-Preset was called by script or manually via mouse/menu.
So my observations are
it’s depends on the plugin (Arturia and maybe others as well)