Your ROOT_URL in app.ini is http://git.osmesh.ru/ but you are visiting https://git.osmesh.ru/MOS/OpenBoard/commits/commit/4707745ca044459053c7d78258bd50022a8c16c9/resources/library/applications/OpenStreetMap.wgt/api/theme/default/style.css
You should set ROOT_URL correctly, otherwise the web may not work correctly.
This widget allows user to browse map using OSM tiles, from openstreetmap.org (classic view) and opencyclemap.org (relief/landscape view).
The API to translate query to coordinates is from Geonames, which provides a key limited to 2k request/hour. Open-Sankoré could register a normal key or contact the administrator to get an unlimited key.