Multiple Page Libraries on site

A SharePoint user is facing a unique challenge modernizing wiki pages within a legacy subsite. This classic Team Site utilizes the STS#0 template and contains two page libraries. The pages to be modernized reside in a custom page library, which only supports the "Wiki Page" content type. Modernization using PnP PowerShell fails because the "Site Page" content type isn't available in this custom library. This results in the modernized pages not appearing within the library. The user is puzzled by the existence of two page libraries, something they haven't encountered before. The immediate problem is modernizing over 300 wiki pages. The user is considering using Power Automate to copy the pages to the standard Site Pages library. A significant drawback is the likely need to manually fix internal page links after the move. They seek guidance on the best approach for modernization, given the limitations. The user also seeks an explanation on how the site has multiple page libraries. Any suggestions or insights are greatly appreciated by the user. The primary goal is to efficiently convert the old wiki pages. The number of pages necessitates a solution that minimizes manual effort. The user is hoping that a more streamlined solution exists.