Are explicit keys of i18n really deprecated?

[skhrshin]

I found that explicit keys of i18n were described under the section "Deprecated Features" in the Canvas Wiki document https://github.com/instructure/canvas-lms/wiki/I18n. However, I think explicit keys are still useful since there are cases where a string contains multiple meanings in English and there should be different translation for each meaning. For example, at present, there are three places which are using

I18n.t('For')

in Ruby or

{{#t}}For{{/t}}

in handlebars but there are languages which do not have prepositions, so it should be translated to some other descriptions depending on their contexts. I'd like to specify explicit keys to distinguish the meanings of this string. Is that OK? If not, what is the correct way to give proper translations?