Hi Chris. Have you had the chance to visit Rumbai yet? I'm currently living in Pekanbaru, and Rumbai is just 8km away from my place, and about 15km from Pekanbaru airport. It seems to have transformed into a bustling city, quite crowded and accessible by various vehicles, mostly private since public transport isn't available.
I've seen some old photos of the Rumbai bridge in a heritage house here; maybe from around the time you were born. It's one of the iconic landmarks of this city. And oh my landlord is a retired midwife from Chevron Rumbai Hospital, maybe she was one of the doctor's assistants during your birth

If you ever visit, I'd be happy to introduce you to her.
Anytime of the year it's nice, but I particularly nervous every August-September when the rains lessen, hope there won't be any forest fire smoke. I've had a couple of bad experiences with that in the past.
I usually head to the Rumbai area every weekend for outdoor activities; there's an 'artificial lake' and a mini forest nearby. What's the name of your village? I'd love to help collect memories from there.