Giving us the ability to manually set interface speeds and/or duplex settings would be helpful.

Explain your use case

Say you have a TNSR router and you want to hook it up to an ISP handoff for MPLS or a mux/demux or whatever, their equipment hands off a 10Gbps link to your 10Gbps link, but they may only be providing you 2Gbps bandwidth. This can muddy the waters with OSPF if you don't statically set the link cost. Setting the reference bandwidth to 10Gb and statically setting the speed of the link to 2Gbps would then auto set the OSPF cost of the interface.

Another use case would be if you're connecting a 10Gb interface to a 1Gb interface, or some legacy equipment. I do not know the ins and outs of how TNSR negotiates speed/duplex settings, but it can't be good if TNSR decides that a link is 10Gb when it's effectively receiving 1Gbps on the other end.

Also if you're in a lab environment, like emulated Eve-NG or GNS3, not being able to set the speeds manually results in inconsistencies in how fast the link actually is so you can't get a good idea of what real-world links/routing tables are going to look like.

Describe the problem and propose a solution

I've had all of the above problems. Being able to say "speed 1000" or "speed 10000" would have been able to resolve most of my issues without having to buy more transceivers or rearrange what ports are able to dynamically negotiate speeds. (This is prevalent on the older models of TNSR hardware, where the board's NICS could not negotiate, but the add-on card could negotiate speeds).

Is it a bug?

No, just not a feature.