The previous balloon was steerable, as it could control its altitude to catch different currents.

I don't think we know enough about this "unknown object" to definitively say what it could and couldn't do.

Not unsteerable if you have altitude control + a good model of wind patterns. This is what Project Loon[1] did and I think it's fair to assume the technology might be similar.

[1]: https://x.company/projects/loon/