Die Leihfristüberschreitung erscheint im Bibliothekskonto.

It is a compound noun, which is very common in German.

You can break it down like this:

• Leihfrist = loan period / borrowing period / due period
• Überschreitung = exceeding / overrun / violation

So Leihfristüberschreitung means something like:

• overdue loan
• exceeding the loan period
• overdue status / overdue item

In library language, it usually refers to the fact that the borrowing period has been exceeded.

Die is the definite article for the noun Leihfristüberschreitung.

Here it is:

• singular
• feminine
• nominative case

So the subject of the sentence is die Leihfristüberschreitung.

A good thing to remember is that the gender belongs to the whole noun, not necessarily to the last English word in your translation. In this case, Überschreitung is feminine, so the whole compound noun is feminine too.

In German compounds, the last part of the compound determines the gender.

Here, the final part is Überschreitung, and die Überschreitung is feminine.

So:

• die Überschreitung
• therefore die Leihfristüberschreitung

This is a very useful rule for German compound nouns.

erscheint is the 3rd person singular form of erscheinen.

Basic meanings of erscheinen include:

• to appear
• to show up
• to be displayed

In this sentence, it means something like:

• appears
• is shown
• is displayed

So this is not about physically appearing in a room. It is more like information appearing on a screen or in an account.

Because the subject is singular:

• die Leihfristüberschreitung = one overdue notice / one overdue status

So the verb must also be singular:

• Die Leihfristüberschreitung erscheint ...

Compare:

• Die Leihfristüberschreitung erscheint = singular
• Die Leihfristüberschreitungen erscheinen = plural

im is a contraction of:

• in dem → im

So:

• im Bibliothekskonto = in the library account

German very often contracts in dem to im.

It is dative case.

The preposition in can take either:

• accusative for movement toward somewhere
• dative for location

Here, nothing is moving into the account. The overdue entry is located / displayed there. So German uses the dative:

• im Bibliothekskonto = in the library account

Also, das Konto is neuter:

• das Bibliothekskonto
• in dem Bibliothekskonto
• im Bibliothekskonto

That -s- is a linking element in a compound noun. In German, this is often called a Fugen-s.

So the word is built like this:

• Bibliothek = library
• Konto = account
• together: Bibliothekskonto

This linking -s- does not usually have a meaning by itself. It just helps join the parts of the compound in a way that sounds natural in German.

The sentence follows normal German main-clause word order:

• Die Leihfristüberschreitung = subject
• erscheint = verb
• im Bibliothekskonto = prepositional phrase

So the structure is:

Subject + verb + location

That is very similar to English word order here:

The overdue entry appears in the library account.

Yes. German often allows several natural alternatives. For example:

• Die Überschreitung der Leihfrist erscheint im Bibliothekskonto.
• Die Leihfristüberschreitung wird im Bibliothekskonto angezeigt.

The second version, with wird ... angezeigt, can sound especially natural in technical or interface language because it clearly means is displayed.

Still, the original sentence is understandable and grammatically correct.

Yes, it is understandable and natural, especially in administrative or library contexts.

It means your library account, for example the place where you can see:

• borrowed items
• due dates
• fines
• renewals
• overdue information

German often prefers these compact compound nouns where English might use a noun phrase like library account.

There actually is one, but it is hidden inside im:

• im = in dem
• and dem means the in dative masculine/neuter

So im Bibliothekskonto already includes the idea of in the library account.

That is why German does not need an extra separate article there.