Time intervals improvement

[adripo]

• I have read the contributing guidelines and I agree with the Code of Conduct
• Have you checked that there aren't other open pull requests for the same changes?
• Have you tested that the committed code can be executed without errors?

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Relates to #647

Improve time intervals visualization.

[marticliment]

before removing the old strings, I was waiting until the General user base has already updated to version 1.6.2, to prevent complaints about disappearing translations.

[adripo]

I reverted cleanup commit