Pywikibot creates a page items with a label equivalent to the page name. See pywikibot.bot.create_item_for_page().
Could you add the ability to set another label via the data parameter?
Because on Wikisource all encyclopedia pages have prefixes and suffixes (Q24509724, Q21281526, etc.). And traditionally labels for them are created with spaces around slashes separating prefixes and suffixes, the bot don't make it (example Q85899318).
Moreover, the consensus about naming is not clear, because according the proposed rule of Wikidata the names of items should be named equivalent to the article’s own name. Currently, this method remove a disambiguation information only from brackets in page name. But it don't know nothing about such prefixes and suffix, which usually are a mark of disambiguation information about the orphography/edition of page. (Like, ЭСБЕ/А, ЭСБЕ/А/ДО, ВЭ/ВТ/А, ТСД/А/ДО, ТСД/А, etc. Where A is article name; prefix is the enc. abbr.; ВТ, ДО, СО - page orphography.)
So, currently Pywikibot will remove all in brackets from ESBE/A (homonym info), but will not remove it from ESBE/A (homonym info)/OO.