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To make it short, time-space shenanigans transported everything in a 60 kilometers circumference around an old space-based particle collider to the year 1855.

The particle collider was in geosynchronous orbit with Earth, in a region of space that was heavily packed with space junk: Pieces of old ships, discarded satellites, remains of an orbital shipyard.

Most pieces are no larger than a baseball, some are as big as modules of the ISS, and there are three big pieces that are the remains of the space shipyard and the fragmented particle-collider that are each as big as the whole ISS.

Could anyone on Earth, on the year 1855, detect the anomaly?

Absolutely not, because it would not even be close to the earth. Literally light years would separate where the same co-ordinates were today vs 1855. But if you hand wave that inconvenient detail aside, the orbital velocity would not be the same between the two periods of time, and things would scatter. But if you hand wave that away, the sun and moon would not be in the same position. And if you hand wave that away,...

Well, you get the picture.

Lots and lots of handwaving the inconvenient details away.

But once all is said and done, and the details tucked away, dismissed, or taken care of, Sputnick was visible by the naked eye. Or at least the booster was.

Have a look at this question in Space.SE, a sister site of World Building:

Are any geosynchronous satellites visible with the naked eye?

And the answers:

If you're extremely lucky with weather and other conditions from where you're observing (especially the light pollution, described e.g. by Bortle scale, should be as low as possible to detect such faint objects), you might be able to see some [satellites in geosynchronous orbit] with powerful binoculars or a hobbyist-grade telescope...

And

...they [satellites in geosynchronous orbit] are easily seen with a small telescope on a sturdy mount. March and September are the best times. Use an app to help you. My favorite way is to keep M11, the Wild Duck Cluster, in view with a medium power eyepiece. Every few minutes, a "star" will slowly track through the southern edge!

Victorian telescopes were comparable to nowadays amateur telescopes, and on top of that light pollution was less intense in victorian times than nowadays.

However, it would still take some luck to find even the larger pieces. Space is huge and you can't just scan the whole night sky with a telescope. Once a competent astronomer finds them, though, they will be able to take note of their keplerian orbital elements (see graphic below) and thus predict their position at anytime with great accuracy.

Absolutely, yes, objects as large as your criteria could have been observed in 1855.

There were several very good observatories at the time, for instance

this

Or this reference

Sydney Observatory began operations in 1858 on a small hill located
near Sydney Harbour. It is best known for its involvement in the
observations of the 1874 transit of Venus and for its participation in
the International Astrographic Catalogue project. The Observatory
remained a working observatory until 1982 when it came under the
auspices of the Powerhouse Museum and became a museum of astronomy and
a public observatory.

Light and atmospheric pollution was minimal in the country.

The population was around 1.2 billion people, so lots of observers.

The critical factor would be where in geostationary orbit it was. it would have to be somewhere over the equator, and over a land mass. Not too many choices. Chances of it being seen diminish the closer it gets to the middle of either ocean.

The advantage is, that it would have to be over the equator, and the equator is primarily in the planetary elliptic plane of the solar system. The planets would be a very good target for astronomers, and so a lot of the time they would be looking roughly in the same plane as the debris. This greatly increases the chances of them seeing it.