First time booking a RTW fare. Booked a DONE3 ex-Japan using the Oneworld website and then ticketed with JAL.
Overall, good experience.

Lessons learned:

• The booking will disappear from JAL MMB almost immediately, but remain accessible on all other OW airlines. As soon as it's ticketed, you can access it again and select JAL seats, etc.
• Cancellation seems to be possible online, but not changes (unsurprisingly).
• Ticketing through JAL was painless. when I called the local English-language reservations desk, I was connected immediately. The agent knew exactly what a Oneworld Explorer fare was and how to ticket it. I needed to wait an hour for a call back, but she confirmed the price was exactly as quoted online. I was not charged a booking fee– a pleasant surprise!
• Payment was through a web portal sent via SMS. I could not receive the SMS while on the phone. Ideally, have a separate phone ready to receive the text. Otherwise, they payment link remains valid for an hour and doesn't need to be used while on the phone.
• Ticket needed to be paid by the passenger.

Unfortunately, I lost my opportunity to fly new JL business class (A350) because I was worried about ticketing my first booking after it failed to load on JAL MMB. I waited ~28 hours for it to auto-cancel and then booked again, but the OW tool no longer offered the necessary feeder flight. Probably could have tried discussing with the agent, but given this is my first time, I was a bit nervous about messing it all up.

The OW web tool is functional but not ideal. For example, originating from Osaka, there was mysteriously no availability returning to Tokyo at the end of the trip, but loads via Tokyo to Osaka. Does anyone have experience doing the complete booking through JAL reservations rather than through the website?