When I did a search for "what time is it cet", I got what looked like the correct time. I got distracted and my brain blanked, so I forgot the result and a few minutes later I did a search for the exact same query. I noticed that strangely the minutes value was off by 7 minutes however.
If you even change the capitalization such as querying "what time is it CET", you will get a new correct answer. So it appears to be caching the results of the time query in some way. In each of these cases, if I search for the same query I used before, I get the original value I got when I made the query. It appears like the cache timer is in the 10-15 minute range, as a query I used while testing this started working after I didn't use it for about that long.
Repro's on both mobile and desktop.
1) Search for "what time is it cet"
2) Note the time returned
3) Wait 5 minutes
4) Search using the exact same query from step 1
5) Note the time is the same as what you originally got, instead of being up to date with the current time
The time should always be up to date and accurate to the current time