You can set up the different default languages for your editable elements (instances) on the same page using the init() WProofreader initialization in a bundle with the lang and syncOptions parameters. To do so, please follow the next steps:
1) Initialize WProofreader using the init() method when you clearly know in which control you want to initialize WProofreader which provides additional management options.
2) Pass the language using the lang parameter and the appropriate shortcode in WEBSPELLCHECKER.init.
3) Disable synchronizing ignore options and languages between all the created WProofreader instances using the syncOptions in WEBSPELLCHECKER_CONFIG.
syncOptions: false,
4) Also, it would be great to check and, if needed, disable storing of WEBSPELLCHECKER options such as language between browser sessions using disableOptionsStorage in WEBSPELLCHECKER_CONFIG.
disableOptionsStorage: [lang],
