Hi Amit,
You can treat the label like a regular standard field. Just make sure to check the placeholder setting "do not show in form" and "not relevant to workflow". Just enter the label text in the default value field. Then change language varian, edit the template, and edit the placeholder setting again, and you can set a different default value for that language variant. This way, it is more out of box and let processing.
However, if you prefer to use rendertag, instead of using Context:CurrentLanguageVariant.Key, just use <%inf_current_language_variant%>.
Best,
-Jian