Security problems raised by staff and unions, which have delayed the transfer of more than 100 juvenile detainees still held in a Western Australian adult prison for over six months back to a juvenile detention facility, are "not rocket science" and should be fixed, a review into the juvenile facility has found.

The review into a January riot at Banksia Hill juvenile detention centre and the subsequent temporary transfer of the child detainees to Hakea prison found that there was not an appropriate level of rehabilitation service available in the Hakea facility and – despite a deadline of late August – it was "likely to be several months" before all detainees were returned.

"The immediate challenge facing the department is the safe and prudent return of detainees to Banksia Hill. It is currently targeting the return to begin in late August 2013 but there is no certainty," wrote inspector Neil Morgan.

Guards have refused to return to work at Banksia Hill until security is increased, however the report found that the focus on "hardening up" the facility was not the only means to stabilisation, finding numerous weaknesses in its security culture.

"Some things are not rocket science and should be capable of resolution with goodwill and good management," Morgan said.

"Idle, bored children will invariably become frustrated and are very likely to act out their frustrations. Bars and grilles will not stop this and it is essential that Banksia Hill return to providing a full and active regime including rehabilitative programs and recreation."

He concluded that the current regime in place at the juvenile facility was unsuitable for young people in detention "because of shortfalls in education, programs and recreation, and because of continuing lockdowns".

Maryann Mackay, an outspoken advocate and aunt to many of the young detainees – the majority of whom are Indigenous – said these efforts to physically strengthen the facility were unnecessary.

"That's only for the guards' satisfaction," Mackay told Guardian Australia. "At the end of the day, these are children that we're talking about, not violent, hardened serious criminals."

Mackay said there was concern for the mental health of the children, many of whom come from traumatised homes and have now been in the adult prison for over six months.

"I wouldn't be surprised if there was further acting out behaviour, because these kids don't know what's going on. Kids need routine and stability and these kids are not getting any of that whatsoever," she said.

WA's corrective services have been working to repair the facility after detainees rioted, damaging 108 of the 240 cells. They did not, however, target staff or attempt to escape. Detainees moved to juvenile facilities at Hakea prison have faced excessive rolling lock downs and strip searches as some were transferred back and forth between the two facilities.

A supreme court hearing in May found the decision to move the children to Hakea was legitimate, but conditions were "less than optimal".

Morgan's report concluded that the initial three-week period in the aftermath which included "near total lockdown" of detainees "was not reasonable and was not necessary by way of risk management".

Morgan observed that the use of restraints and strip searches had become routine in many instances when it should be based on individual assessments.

The report said that, in the two years leading up to the riot, the centre was a "tinderbox" and events were "entirely predictable" from at least 18 months prior, due to poor management and the amalgamation of Banksia Hill and Rangeview remand centre, which ultimately "became a case study in how not to manage change".

The report also said that the initial response to the riot was "generally good and in many respects exemplary", crediting the fact that no one was seriously injured. However, it also noted that sufficient checks on the welfare of vulnerable children who remained in their cells were not done.

The report estimated a tripling of the department's budget was needed for at-risk youth services, and said there were "strong arguments" for a new and separate department.

The Community and Public Services Union (CPSU), representing the centre's staff, welcomed the findings but said a new agency for youth justice would just be "like shuffling the deck chairs on the Titanic" unless the Barnett government increased funding and resources.

CPSU branch secretary Toni Walkington said they had raised issues with various corrective services ministers but were ignored.

Shadow correctional services minister Paul Papalia told Guardian Australia the current WA government compromised juvenile detention and rehabilitation when they amalgamated Banksia Hill and Rangeview.

"The long-term sentenced juveniles had their stability undermined and disrupted. That is what set the conditions for the riot," Papalia said.

"It was entirely predictable and it was all done because the [Barnett] government wanted a cheap option for the new men's prison as promised at the 2008 election."