Yes, the manuals I was able to find from HP only show that you can see the fan speeds in BIOS Setup, but there is NO info on whether you can adjust anything for them. So I suspect you cannot. The system MAY actually control those fans speeds for you, but it is hard to tell.
Now, your concern was based on a display of info generated by HWMonitor. As a general rule (I do NOT know whether this applies here), many third-party tools for checking system data need to be configured or calibrated for the individual mobo you are using. This can involve both identifying which actual device (like, which fan on which mobo header) is being displayed versus the label that the utility shows, AND ensuring that the reading is correctly calibrated. Basically, such utilities cannot possibly know all those things for all the mobos sold in the last few decades! The only data you CAN rely on is that generated by BIOS Setup, or sometimes by a utility supplied by the maker of that mobo (or complete system) that runs as an app under Windows IF there is one. Without that latter, you are only able to rely completely on what BIOS Set.up shows you, and that cannot be used during normal operations. So that is pretty limiting, But the bottom line here is that your concern is based on info that is NOT clear at all. Further, at least at minimal workload using BIOS Setup, the speeds of both the CPU cooler and the case fan are reasonable. So I think you do not need to worry.