Question

How to set several recognition languages in FineReader Engine?

Answer

Call the SetPredefinedTextLanguage method of the RecognizerParams object with names separated with commas, for example:

// C#
DocumentProcessingParams documentProcessingParams = Engine.CreateDocumentProcessingParams();
PageProcessingParams pageProcessingParams = documentProcessingParams.PageProcessingParams();
RecognizerParams recognizerParams = pageProcessingParams.RecognizerParams();

recognizerParams.SetPredefinedTextLanguage("English, French, German");

Additional information 

List of predefined languages in FineReader Engine