In order to get the logs, you can start jami with the -d option. The documentation is here:
Here is an outline of the procedure:
First, you need to start a terminal or command prompt (cmd.exe on Windows), then you go to the Jami install directory, generally C:\Program Files\Savoir-Faire Linux\Jami
In that case, you need to type the following command in your terminal :
cd C:\Program Files\Savoir-Faire Linux\Jami
Then, you type Jami.exe -d -f %localappdata%\jami\jami.log on the command prompt and you will get all the logs in colors 
(quite overwhelming…) displayed in the terminal.
With the previous syntax, the complete logs will also be written in the jami.log file. To get that file, you simply need to type %localappdata%\jami\jami.log in your Windows file browser.
When I messed 
with Jami to add a voip.ms account, I had a similar problem where the program would fail to initialize properly. What I did is install an older version of Jami (e.g. 2024-12-19 here Index of /windows/archive), reinitialized the settings (in my case I had wrongly enabled SDES and TLS encyption in the Advanced settings, so I disabled these options). Eventually, I was able to upgrade to the latest Jami version again.