I have no experience either. Saw this PR recently (cannot find an English version):
https://press.jal.co.jp/ja/release/201912/005417.html
It says JL is expanding its vacation program "Japan Airlines Vacations" to US/Canada as of Sep 30/Oct 31 of 2019, so I believe it's a new thing.
I tried searching a few simple round trips in J from LAX/SAN to TYO but prices don't look very appealing to me. Amex IAP + separate hotel would be cheaper. Maybe I need to search more.