I would be installing 4"x4" joist hangers between the rafters and set in pieces of 4x4 P.T. lumber. If you are hanging the bed with chains, I'd drill through the 4x4's at the appropriate spot and insert bolts with washers and nuts on top. Good luck.
Based on your information I would have to go with toggle bolts.
C-90 Hollow Block (1 1/2-inch wall)
An anchor sized at 1/8 inches can take 310 pounds, at 3/16 inches it can take 700 pounds, and a 1/4-inch anchor in a 1 1/2-inch thick wall can take 1,390 pounds. This increases to a whopping 3,620 pounds for a 1/2-inch anchor with a 1 1/4-inch embedded depth.
Bolting will work short term, but will kill the tree long term (a few years) The tree continues to grow. Your system needs to allow for the fasteners to be let out to not cut the sap flow.
The usual way to fasten a serious tree house to the trunk uses special hardware. Example here: https://www.nelsontreehouse.com/blog/2017/2/21/hardware-highlight-tab
As requested, The reddish color makes me want to ask if it is madrone, does it shed it’s bark? ,Are the leaves mid size thick or leathery and almost feel waxy? If this is what it is I would not use it for support. Madrone is very hard and cracks and splits easily, it is a large one but I would verify the type before trying to use as it might work for now but ...
I would hire a structural engineer to give me a report on the existing conditions and include any needed support for that beam. Tell him your ideas and intentions so he can advise you what is needed or required.