RE: Even if you use the shortcode [connections_form] for both the English and Chinese language pages, it will automatically use the translations for the form?
I don’t see why not. Other plugins switch there language too if the language is switched by the switcher, correct? Assuming the other plugins have a T. Chinese translation.
RE: how do I apply the PO/MO, do I have to send you the translated PO/MO files in order to see the updates?
Well,if you use the Loco Translate plugin, you simply search for and translate the strings you need right in the WP admin. It takes care of creating and placing the files in the correct location. However, you should send me the PO files (not the MO). That way I can include them in updates so you do not lose your work.