I have checked prices and flight status for Mr. Tadashi as you requested.
About second plan JL5032 and JL5031, these flights has operated by Thai airways.
And the price is quite expensive (Economy class around 41,000 THB).
However JL727 for return flight is available only business class,
If passenger not preferred business class, I would like to offer you alternative plan
So please kindly see the below itinerary.