There are many mysteries about this locomotive. Is it really an HPS? Where did it come from? If it came from East Pakistan, how did it come?
Presuming that it was owned by the Pakistan Eastern Railway (the name used from 1961 to around 1972), the most logical answer to this is that it was operating a scheduled passenger service between East Pakistan and Calcutta (Sealdah). The normal practice is that the locomotive would be changed either at the last station in Pakistan or the first station in India. That is being followed even in 2022.
These services were abruptly stopped during the 1965 war. At some point during this war, this locomotive probably happened to enter India on its way to Gede or Bangaon or Petrapol and was “captured” by India. There was no land war in the east in 1965, although there were air attacks by both sides.
No scheduled passenger services ran between India and East Pakistan/Bangladesh until 2008. It is known that goods services had started some years before that. And military trains ran between India and East Pakistan/Bangladesh during and after the 1971 war.
There may be various other ways in which the locomotive came to be in India, but I am not going into them. It is just possible that it was brought into India in 1971-72 as some kind of “war trophy” as some Pakistani tanks were. But it was not displayed in public until recent years.
We now pick up the story in 1985, when a British railfan took this picture in 1985 at Bandel:

You can just make out the number 32 on the cab.
A few years ago this loco made its way to the Howrah Railway Museum. This is what you will see now:

Numerous other pictures can be found on the net. It has been painted in a nice shade of green. The tender is that of a different type of locomotive (but this is not so significant as there were many mismatched locos and tenders over the years).
What is significant is the inscription. It is clearly made by someone from the Howrah museum who thought it should be like this.
The questions are:
Bangla was one of the official languages of Pakistan from around 1954 to 1972 or a bit later. Pakistani postage stamps and other government documents did have Bangla as well as Urdu during this period. Station signs in East Pakistan then had inscriptions in both languages, as you can see in these pictures from the 1971 war:


But why would anything operating in East Pakistan at that time have Urdu and not Bangla?
Here is a rather bad picture of a PER coach:

One can just make out the Bangla inscription “Purbo Pakistan Railway”, followed by PE (the official abbreviation) followed by an Urdu inscription. (Perhaps some reader will be able to say what is written in Urdu).
A typical Pakistani stamp issued in 1971 or earlier, overprinted with Bangladesh:

Now come back to the present-day picture.
It says “East Pakistan Railway” but nothing of that name existed in the past. As mentioned above, it should be “Pakistan Eastern railway” or PE. Wagons and coaches were also marked PE.
The Urdu inscription has been checked by a couple of friends who know the language. It reads “Purvi Pakistan Railway”. That is not Urdu (as the first word would correctly have been something like “Mashriqi”). In fact, the Urdu inscription seems to be transliteration from Hindi “Purvi” rather than Bangla “Purba”. Please correct me if this is wrong.
Conclusion: It is interesting to speculate on various questions:
If it is not an HPS, why was this marked as one?
The records show that HPS 32 was listed under the PER. (p 38 of Hughes, Vol 1 (1990), also p.82 of Hughes, Vol 4 (1996)). However, the manufacturer and date of manufacture are not given.
How did it come to be in places far from the border, such as Bandel?
And whoever painted the inscriptions in English and Urdu was not instructed properly. (Why? There are certainly some people in West Bengal who know Urdu properly.)
While this probably isn’t something to worry about, it just shows the shoddiness which is associated with IR’s restoration works. There are many examples of garishly painted locos (Pink? Blue?) plinthed in different parts of the country.