So moreless how finished is this game?
Not even remotely close.
It's 0.19.1, after all.
You can see it that way, but that's not true either.
First, the version number does not indicate how finished the game is. Each version increases the number, but there is no telling how many versions still will follow. It might jump from v 0.25 to 1.0, for instance.
Second, since several releases they mainly deliver a complete story arc per version, so if an update is focusing on one girl, the story for that girl may be considered complete, or at least near to complete.
Currently, I would consider the game nearly complete for those girls:
0.19.1: October 18th 2019 (Eve, Grace, Odette)
0.18.5: June 4th 2019 (Jenny 2)
0.18.0: May 2nd 2019 (Jenny)
0.17.5: Dec 16th 2018 (Daisy)
0.17.0: Nov 23rd 2018 (Diane)
0.16.0: July 25th 2018 (Roxxy, Missy, Becca)
0.15.1: April 15th 2018 (Ms. Bissette, Ms. Ross, Ms. Dewitt, Ms. Okita)
0.14.5: December 19th 2017 (Debbie)
0.14.3: November 1st 2017 (Aqua)
0.14: October 13th 2017 (Mia, Helen)
0.13: August 21st 2017 (Erik, June, Mrs. Johnson)
The amount of content varies. I would say, Jenny has the most, Diane the least (apart from Aqua and Daisy, which have been surprise updates). Other girls have isolated scenes. And I know that Erik is not a girl