How did the Soviet press talk about the opposing forces (mujahideens) during the Soviet-Afghan war?

Based on the 1990 Conflict Quarterly piece (found/suggested by Dan M in comments), there were significant difference between Brezhnev and Gorbachev times, although change during the latter was rather gradual.

During Brezhnev's time, there was near total censorship of the conflict. It was not called a war in the Soviet press, and one journalist who spoke of "invasion" was promptly dismissed. The internal opposition within Afghanistan was minimized, at best compared to "Basmachi bandits". The main source of the problem was ascribed "around" Afghanistan. Namely the Zia regime (of Pakistan) was described as an American puppet that would soon crumble, and with it the problems of Afghanistan. Occasionally, the Chinese were blamed as well. There was no public acknowledgement of the scale of Soviet personnel losses, nor much admission that they were engaged in significant combat operation, the press focus being on covering what might be called "hearts and minds" operations, in other contexts:

In February 1980, for example, Pravda reported Boris Ponomarev (then head of the International Department of the Central Committee of the Communist Party) as claiming that the "Afghan authorities and the Afghan population display a friendly attitude towards the Soviet servicemen" and that "no clashes are taking place between Afghans and our soldiers, as all kinds of 'voices' unscrupulously and long-windedly claim." [...]

The articles that appeared during the period invariably depicted the Soviet army in the historical, Russian terms and the Soviet troops as pursuing their duties selflessly. Occasional photographs showed them planting trees, restoring mosques, and building hospitals, schools, residential complexes and roads.

[...] Meanwhile, [the Soviet press] showed a particular interest in projecting the views held by the Pakistani opposition parties on the Afghan crisis. As these views were mostly opposed to Islamabad's policy, Moscow's purpose was to highlight the unpopular nature of Islamabad's policy in Afghanistan.

Generally, the central Soviet press appears to have focused on this broader foreign policy perspective during this time. Only the press closer to the front, in the Central Asian Soviet republics was more focused on discrediting the Mujahideens

In the Soviet Central Asian press, however, more effort than in the central Soviet press was directed at discrediting the Afghan Mujahideen. There were more specific references to their atrocities, crimes and backwardness. There was also a visible concerted effort to prove that the support for the rebels was narrow and constantly shrinking. Numerous reports in the regional press highlighted the Mujahideens' ruthlessness, which included crop-burning, cutting trees down, laying mines disguised as toys, destroying schools, hospitals and mosques, and attacking the civilian population. The latter activity included the assault, torturing and killing of women and children, as well as burning people alive.

Things gradually changed during the Gorbachev era. First came admissions of (some) casualties and public medal granting to troops. Around 1987 (this was some 8 years into the conflict), as the Soviet leadership was by then thinking of ways to extricate the USSR from the conflict, there were more frank assessments published in the Soviet press, sourced from fairly high level military officials (like Gen. Aleksei D. Lizichev or Major Gen. Kim M. Tsagolov), first of the Soviet casualty figures (then said to be around 35,000 seriously wounded) and of the scale of the opposition fighters within Afghanistan (put at 100,000) as well as the scale of their attacks (around 2,000 in half a year). As the Soviets were trying to establish some kind of dialogue with some of Mujahideen, some of their commanders were openly praised in the Soviet press, while it simultaneously criticized the Afghan [PDPA] government:

In an editorial, Pravda conceded that "far from all people in Afghanistan," even "the working sections of the population," had not accepted the April Revolution." [Soviet academician] Nodari Simonia [...] added that [...] the PDPA [...] had a "very narrow base" and "the country [Afghanistan] was not ready for such radical [communist] reforms".

A Soviet soldier sarcastically remarked to Artyem Borovik, "If I did not read [Soviet] papers, I would never know that we are in full flush of 'reconciliation.'" [...]

Concurrently, the media coverage of many Afghan field commanders became extremely positive and Artyem Borovik, even described Ahmed Shah Massud, a field commander in the northern provinces, as "bright and diplomatic." Such efforts were coupled with changes in the Soviet lexicon: instead of referring to the resistance as bandits and mercenaries, they were now referred to as the "misguided" Afghans. Gorbachev himself, in his speech at Vladivostock, labelled them as "patriots living on the other side of the border." Artyem Borovik later highlighted the irony: "Now, even in our press, we do not call the Mujahideen enemies. Simply, 'the armed opposition'. What kind of war is it where there is no enemy ?"