VERIFIED SOLUTION i

How to set the GUI and spellcheck language for the Editor in custom integrations of EngageOne

Product Feature: Installation / Upgrade
You must specify the speller folder path in “template.properties” file. 
A DOC1 speller folder comes with 5.6 Designer installation and its default location is “C:/Program Files/PBBI CCM/DOC1/Designer/Client/spellers”. will also have to adjust the LCID in “template.properties” file.

Below are different valid LCID values:
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English - Great Britain 2057
English - United States 1033
German – Germany 1031
German – Austria 3079
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That template properties file is the one you refer to in the call to LoadContents (refer to the EO Programmer's Guide (GEN2) under "Editor Methods" and "Editing a document")
UPDATED:  November 6, 2017