Translations template update and fixups.

[VlasovVitaly]

Couple of fixups after PR #13283.

Added lots of comments to translators.
Added missing strings from use_action field ("message")

I found strange effect in data/json/effects.json

     {    
        "type": "effect_type",
        "id": "darkness",
        "apply_message": "Your vision flickers and goes gray!",
        "remove_message": "The world flickers back to normality.",
        "rating": "bad"
    },   

It seems valid, but don't have description. I didn't touch this effect_type.