In foro de novo decreto diu disputatur, sed sine querelis concordia difficilius servatur.

Because disputatur is an impersonal passive.

The verb disputo, disputare can be used intransitively, meaning to discuss / debate. In Latin, an intransitive verb can form an impersonal passive in the 3rd person singular, often translated as:

• people discuss
• there is discussion
• it is being discussed

So de novo decreto disputatur means something like:

• people are debating the new decree
• the new decree is being debated
• there is debate about the new decree

There is no expressed subject like they.

Because in with a meaning of location takes the ablative.

Here in foro means in the forum / in the marketplace / in the public square, so it answers where?

• in foro = in the forum → ablative

By contrast, in with the accusative usually shows motion into something:

• in forum = into the forum

So the case depends on whether the phrase expresses location or movement.

The preposition de regularly takes the ablative and often means:

• about
• concerning
• regarding
• sometimes from/down from, depending on context

So in this sentence:

• de novo decreto = about the new decree

Both words are ablative because the adjective must agree with the noun:

• decreto = ablative singular
• novo = ablative singular, agreeing with decreto

Because novo is an adjective modifying decreto, and Latin adjectives must agree with their nouns in:

• case
• number
• gender

Here:

• decreto is ablative singular neuter
• novo matches it: ablative singular neuter

So de novo decreto is a normal noun phrase meaning about the new decree.

Diu is an adverb meaning for a long time or long.

It modifies disputatur, so:

• diu disputatur = the discussion goes on for a long time / people argue for a long time

It is not an adjective, so it does not agree with anything.

Because sine always takes the ablative.

So:

• sine querelis = without complaints

Here querelis is the ablative plural of querela.

This is just like several other Latin prepositions that require a fixed case.

Latin often uses the plural where English might use either singular or plural.

So sine querelis can suggest:

• without complaints
• without grumbling
• without quarrels, depending on context

The plural gives a general sense of repeated or multiple complaints, but it does not have to mean a specific countable number.

Because concordia is the subject of servatur.

In the second clause:

• concordia servatur = harmony/agreement is preserved

Unlike disputatur, which is impersonal, servatur here has a real subject, namely concordia.

So:

• concordia = nominative singular
• servatur = is preserved / is maintained

Because the sentence focuses on the state of concordia rather than on the people preserving it.

• servatur = is preserved / is maintained

Latin often uses the passive when the agent is unimportant, obvious, or left unstated. English can do the same:

• harmony is maintained

If Latin wanted to say someone preserves harmony, it could use an active form instead.

It is an adverb, specifically the comparative adverb of difficulter.

So:

• difficulter = with difficulty
• difficilius = with more difficulty / more difficultly

It modifies servatur, not concordia.

That is why it does not agree with concordia. If it were an adjective modifying concordia, it would have to match its gender, number, and case. But here it stays in adverb form.

A comparative adverb does not always need an explicit second term.

So difficilius servatur means:

• is preserved with greater difficulty
• is maintained less easily

The comparison is understood from context, something like:

• more difficultly than one might expect
• more difficultly than otherwise
• more difficultly than when there are complaints, depending on how the sentence is interpreted

Latin often leaves the second part of the comparison unstated.

Latin word order is more flexible because grammatical relationships are shown mainly by endings, not by position.

So the sentence can place words for emphasis or style:

• In foro sets the scene first
• de novo decreto gives the topic of debate
• diu highlights the length of the discussion
• sed marks the contrast
• sine querelis comes early in the second clause to emphasize the condition
• concordia appears near servatur as the subject of that clause

A very literal English-like order would sound something like:

• In the forum, people discuss the new decree for a long time, but harmony is preserved with more difficulty without complaints

Latin does not need to keep that order.

It can mean either, depending on context.

Common possibilities include:

• harmony
• agreement
• concord
• social unity

A learner should remember that Latin words often cover a range that no single English word matches perfectly. Here concordia suggests a state of people getting along or staying united.

In theory de can sometimes mean from or down from, but not here.

With a verb like disputatur, the natural meaning of de + ablative is about/concerning:

• de novo decreto disputatur = there is debate about the new decree

So the verb strongly points to the meaning about, not from.