How to express 踏实 accurately?
踏实 seems to have two groups of meanings:

[1]


dependable; sure and steady
at ease; free from anxiety; having peace
of mind


[2]


practical; realistic; pragmatic
down-to-earth


When it comes to describing people, I'd choose "dependable" or "down-to-earth" depending on which meaning you need. If you could provide some more context, it would help in choosing the best word.