It seems as if the link to download the English version is actually downloading the Chinese version.
Clicking on the download link for Toad for Oracle 12.5.1 Installer (for 32 bit Oracle client) shows the address https://support.quest.com/toad-for-oracle/12.5.1#
Toad for Oracle installation error message: 剏ⵁ㈱㔱㨴吠华挺畯摬渠瑯爠獥汯敶猠牥楶散渠浡
The correct English installer is being downloaded.
This is due to an unsupported Oracle client used in connection.
Use a supported Oracle client per the Toad for Oracle system requirements.