La guionista del documental explicó que el guion era más difícil de lo que parecía.

Guionista is a common-gender noun. That means the noun itself stays the same for both men and women, and only the article changes:

• el guionista = the male scriptwriter
• la guionista = the female scriptwriter

This is very common with nouns ending in -ista, like el/la artista, el/la periodista, el/la dentista.

Del is the contraction of de + el.

So:

• del documental = de el documental = of the documentary

In standard Spanish, de + el almost always becomes del. The main exception is when El is part of a proper name, such as de El Escorial.

They are related words:

• guion = script, screenplay
• guionista = scriptwriter, screenwriter

So in this sentence:

• la guionista is the person
• el guion is the thing she wrote or worked on

English does this too with pairs like novel / novelist or art / artist, although the endings are different.

In modern standard Spanish spelling, guion is normally written without an accent mark.

The current academic norm treats it as a monosyllable, and monosyllables usually do not take a written accent. So the recommended spelling is:

• guion

You may still see guión in older texts or from native speakers who prefer the older spelling, but the standard modern form is guion.

Explicó is in the preterite because it refers to a completed action in the past: she explained it at some point.

The preterite is often used for events that are seen as finished:

• explicó = she explained
• dijo = she said
• contó = she told

If the sentence had explicaba, that would suggest an ongoing, repeated, or background action, which is not the idea here.

They are in the imperfect because they describe a state or appearance in the past, not a single completed event.

• era más difícil describes what the script was like
• parecía describes how it seemed

The imperfect is very common for background description, states, and appearances in the past.

So the contrast is:

• explicó = a completed action
• era / parecía = ongoing past description

They do two different jobs.

1. In explicó que..., que means that and introduces what she explained:

   • explicó que el guion era... = she explained that the script was...

2. In de lo que parecía, the que is part of the expression lo que, which means something like what or how it in this context.

So even though both words are que, they are not doing the same thing.

After a comparative like más, Spanish often uses de lo que when what follows is a whole clause rather than just a noun.

So:

• más difícil de lo que parecía = more difficult than it seemed
• más fácil de lo que pensaba = easier than I thought
• menos caro de lo que esperaba = less expensive than I expected

By contrast, with a direct noun comparison, Spanish normally uses que:

• más difícil que el anterior = more difficult than the previous one

So de lo que is a very common comparative pattern.

Here, lo is neuter. It does not refer to a masculine noun like el guion.

In expressions like lo que, Spanish uses lo to refer to an idea, situation, or unspecified thing:

• lo que parecía = what it seemed / how it seemed

So in this sentence, lo que parecía refers to the impression or appearance the script gave, not to a specific masculine object.

Because difícil is an adjective with the same form for masculine and feminine singular.

Compare:

• un guion difícil
• una tarea difícil

The adjective stays difícil in both cases. It only changes for number:

• un guion difícil
• dos guiones difíciles

So here it agrees with el guion in number, but not with a special masculine ending.

Each one has an accent mark for a slightly different reason:

• explicó: the accent shows the stress is on the last syllable, which helps distinguish the past tense form.
• difícil: words ending in a consonant other than n or s are normally stressed on the last syllable, so the accent is needed to show the stress is actually on -fí-.
• parecía: the accent helps show that -ía is pronounced as two syllabic parts, not compressed into one.

So the accents are not random; they follow Spanish stress and pronunciation rules.

Del documental directly modifies la guionista and tells you which scriptwriter we mean: the one associated with the documentary.

So:

• La guionista del documental = the documentary’s scriptwriter / the scriptwriter of the documentary

This order is very natural in Spanish: noun + de + noun is a common way to show possession or connection.

Compare:

• el director de la película
• la autora del libro
• el final de la historia

So this is a very standard structure.