Labels are not adapting in ENGLISH while extending a Fiori App

Hello Experts,

I am trying to EXTEND a Fiori app using SAP Web IDE where i want to CHANGE highlighted label using English language file.

In the extension project, i have created a new EXTENSION (i18n Resource Text Customization) and when i open 'i18n_en.properties' file, i dont see EXISTING LABELS DETAILS as they are displayed in above screenshots. (looks like when i open this file, its not adapting labels for English)

I go ahead , find the required LABEL info and update it

When i run index.html to preview it, this required label info gets updated but others convert into some other language.

any inputs for 2nd and last screenshots?

CC: SAPUI5 Developer Center

Regards,

JK