Is there a gem or something to parse strings like \"4h 30m\" \"1d 4h\" -- sort of like the estimates in JIRA or task planners, maybe, with internationalization?
You can use chronic. It can parse pretty much everything you trhow at it, including "yesterday", "last week" etc.
Update: As the OP points out in the comment, Chronic is for dates, not timespans. See my other answer.