IRISH language advocacy groups believe the acht na Gaeilge included in leaked draft agreement between the DUP and Sinn Féin did not go far enough in protecting the language.
Conradh na Gaeilge said there were "gaps remaining" in the package, while Pobal described the proposed legislation as "extremely weak".
Their assessment of the proposed Irish language act in the draft deal leaked to journalist Eamonn Mallie came as the sister-in-law of former loyalist leader David Ervine said discussions around a deal on an acht na Gaeilge needed to be more transparent to prevent scaremongering among unionists.
Irish language activist Linda Ervine spoke of "silly" rumours she had heard in the period leading up to the collapse of the Stormont talks last week.
Speaking as she attended a meeting in Belfast with the Oireachtas Committee on the Implementation of the Good Friday Agreement, Ms Ervine said unionists had nothing to fear from legislation protecting the Irish language.
"I believe that an act is something that we have in Scotland, we have an act in Wales," she told the Press Association.
"An act here would be different, it would be bespoke for Northern Ireland, but no, I don't think there's anything to fear and I think if you're not an Irish speaker it's really going to have very little impact on your life."
She said rumours of the act's contents may have contributed to fears around changes legislation might bring.
"I think probably one of the saddest things is that people weren't made aware of what was in the act," she said.
"Maybe if people had had more knowledge then it might have been easier, I don't know."
Ms Ervine, who works with the Turas project in east Belfast, said there had been an element of "scaremongering" ahead of the talks collapse.
Former Sinn Féin Belfast lord mayor Niall O Donnghaile, now a senator, said it was an opportunity for members of the Oireachtas committee "to come and hear directly from groups about their concerns but also see the vibrancy of the Irish language in the north".
He said his party "very determined" to secure standalone legislation on Irish.
"I believe from what Sinn Féin have said publicly that that was a core component of the agreement that was reached with the DUP and unfortunately the DUP were unable, it transpires, to deliver on that deal and seal it," he said.
Conradh na Gaeilge advocacy manager Ciarán Mac Giolla Bhéin said his organisation welcomed support for an acht na Gaeilge from the Irish government, Sinn Féin and other parties at Stormont.
He urged the two governments to press ahead with implementing legislation but noted that what was included in the leaked draft deal did not go far enough.
"There are gaps remaining in the package which was revealed to us today, particularly around the visibility of the language, which we call to be included in any future Irish language act," he said.
Pobal director Janet Muller said the text of the leaked documents showed the "depth of mistrust and animosity" towards the Irish language.
"There has clearly been a great deal of work done on this document, and there will no doubt continue to be debate about how much of it was agreed," she said.
"However, in the language section, at first sight it appears to contain extremely weak proposals which would be incapable of protecting and promoting the Irish language in the context of the six counties, precisely because of the levels of hostility which sadly exists in some quarters."
She said the the proposals did not contain any reference to the creation of rights for Irish speakers, which Ms Muller said was a "fundamental issue".
