To Fukui

Which is nearer to Fukui, is it from Osaka or Nagoya?
Is there any normal train to Fukui from either of that city?
How much is the price ?

Fukui is 11 kilometer closer to Osaka than Nagoya. The fare is about 300 yen more expensive from Nagoya. Around 7000 yen from both cities.

You can look it up yourself on timetable websites, as explained below:
https://www.japan-guide.com/e/e2323.html

I just went to Fukui last month, by train seems more convinient from Osaka, and you can use regional pass Takayama Hokuriku pass if you intend to stay around the area up to 5 days

https://www.japan-guide.com/e/e2361_takayama_hokuriku.html

Another discount ticket available for foreign travelers departing from Osaka is the Hokuriku Shinkansen One-Way Ticket reduces the cost to 6000 yen:
https://www.japan-guide.com/e/e2361_jrwest.html

by train seems more convinient from Osaka

I can think of two more reasons for this feeling:
- trains from Osaka are more frequent
- trains from Osaka tend to have the better connections at Tsuruga