Gjestesengen står i gjesterommet enn så lenge.

Because Norwegian usually writes compound nouns as one word.

• gjesteseng = guest bed
• gjesterom = guest room

Then the definite ending is added to the whole compound:

• gjestesengen = the guest bed
• gjesterommet = the guest room

This is very common in Norwegian. English often separates these words, but Norwegian normally joins them.

They mark the definite form, which usually corresponds to the in English.

• en gjesteseng = a guest bed

• gjestesengen = the guest bed

• et gjesterom = a guest room
• gjesterommet = the guest room

So instead of putting a separate word like the in front, Norwegian often adds the definite article to the end of the noun.

Why the endings are different:

• -en is a common definite ending for masculine nouns
• -et is a common definite ending for neuter nouns

Here:

• seng is masculine: en seng → sengen
• rom is neuter: et rom → rommet

In Norwegian, it is very common to use position verbs for location:

• står = stands
• ligger = lies
• sitter = sits

English often just says is, but Norwegian often prefers a more specific verb.

So:

• Gjestesengen står i gjesterommet literally means The guest bed stands in the guest room

This sounds natural in Norwegian because beds and other pieces of furniture are often described with står when they are upright in their usual placed position.

You could say er i gjesterommet, but står i gjesterommet sounds more natural here.

Enn så lenge means for now, for the time being, or so far depending on context.

In this sentence, it means something like:

• the guest bed is in the guest room for now
• this is the current situation, but it may change later

It is a fixed expression. Even though enn often means than in other contexts, here you should learn enn så lenge as one whole phrase.

Examples:

• Enn så lenge bor jeg i Oslo.
  For now, I live in Oslo.

• Alt fungerer enn så lenge.
  Everything is working so far.

Because adverbial expressions like enn så lenge are often placed late in the sentence in Norwegian, especially in simple statements.

The basic structure here is:

• Gjestesengen = subject
• står = verb
• i gjesterommet = place
• enn så lenge = time/limitation phrase

So the sentence flows naturally as:

Gjestesengen står i gjesterommet enn så lenge.

You can sometimes move enn så lenge earlier for emphasis:

• Enn så lenge står gjestesengen i gjesterommet.

That is also correct, but the original version is very natural.

Because i is the normal preposition for being in an enclosed space such as a room.

So:

• i gjesterommet = in the guest room

This is the expected choice when something is located inside a room.

Compare:

• i huset = in the house
• i bilen = in the car
• i rommet = in the room

If you wanted to say A guest bed is in a guest room for now, you would use the indefinite forms:

• en gjesteseng
• et gjesterom

So the sentence would be:

En gjesteseng står i et gjesterom enn så lenge.

That is grammatically possible, though in real life it may sound less natural unless you are talking about one of several possible guest beds or guest rooms. The definite form in your original sentence sounds more natural when both speaker and listener know which bed and which room are meant.

It follows normal Norwegian main-clause word order.

The pattern is:

Subject + verb + other sentence parts

So:

• Gjestesengen = subject
• står = verb
• i gjesterommet = place
• enn så lenge = adverbial phrase

This is standard for a simple statement.

A useful thing to remember is that Norwegian main clauses usually follow the verb-second rule. Here, the subject comes first, so the verb naturally comes second:

Gjestesengen står ...

If another element were put first, the verb would still come second:

• Enn så lenge står gjestesengen i gjesterommet.

Yes, gjeste- is commonly used in compounds to mean something intended for guests.

Examples:

• gjesterom = guest room
• gjesteseng = guest bed
• gjestehåndkle = guest towel
• gjestetoalett = guest toilet

Notice that the first part may appear as gjeste- or gjester- depending on the compound and usage. In your sentence, the established words are:

• gjesteseng
• gjesterom

The important thing for learners is to recognize them as normal compound nouns.