No new growth yet and some vines are stiff & brittle but i'm not familar with this plant so im glad its still alive

You aren't alone. My 'Jennifer' has a couple of leaves that are stiff, and they don't look right to me, even though the rest of the plant looks normal. So I know what you mean. Certain leaves sometimes look like they're going to be the death of the whole plant. Here's a pic. The leaves in question are on the left. I looked closely just now, and most of the leaves are also slightly wrinkled. So. . . back to the old question--is it over watering or under watering? I hate not knowing.

if you just got your plants from thailand, maybe the best thing would be to not expect growth for the next few months or until spring. i got a few from thailand, and right now my goal is just to keep them healthy and alive.

the pottsii i got has a few floppy leaves, but they do seem to be recovering with weekly water and showering of the leaves. a few of the leaves have stiffened.

a couple of the plants are in zip lock bags for humidity. ill probably leave them there for a couple of months. they seem to like this.

right now, several of my hoyas in general are not growing much even though i'm in l.a.

basically, i'm trying not to worry about these new plants from thailand.

If the vines that are stiff and brittle have no leaves on them, they are probably new growth that has withered and died. Common with shipped plants. You can cut those back to live growth.

Don't expect any new growth until Spring, at the earliest. First, the plant will work on establishing/repairing it's root system. This can take a bit of time.

Yes, I got a plant from Thailand and it didn't grow or do anything until the next spring. They do need time to recover.