One of your first comments on this thread used the 'Pakistan did Kargil' canard (ignoring India's own Siachen aggression) to argue against any demilitarization minus validation of the AGPL - you don't see Pakistan making the same argument given Indian duplicity and military aggression in Junagadh, Hyderabad and Siachen when talking about demilitarization in Siachen. Pakistan faces the same risk, that India could back track on any agreement and deploy her military again and take over even more territory.
Actually, this is why India never bothered to take the issue to any international forum for adjudication and/or clarification over the interpretation of the language of the demarcation agreement. The complete phrase is 'thence north to the glaciers' - which glacier? The middle of the glacier, the northern tip of the glacier, the southern tip of the glacier?
All the maps that existed at that time (including some Indian maps which India later rejected under the laughably ridiculous excuse of 'we made an error') supported the Pakistani interpretation of the agreement. Even now, if one looks at India's farcical interpretation, a 'true North' delineation from NJ9842 does not align with India's military deployments on the Saltoro Ridge - that deployment takes a 'North-Western' direction. Therefore, at a minimum under India's own 'true North' interpretation, India would have to hand over the current ridge-lines she occupies to Pakistan.
Based on the maps published by Pakistan, the US and even India (that India later called a mistake) technically the territory was demarcated - India just didn't like the way it was demarcated and deliberately chose to violate the Simla Declaration, the UN Charter and the agreement on the demarcation of the LoC in an unprovoked military occupation of Siachen.
(ii) That the two countries are resolved to settle their differences by peaceful means through bilateral negotiations or by any other peaceful means mutually agreed upon between them. Pending the final settlement of any of the problems between the two countries, neither side shall unilaterally alter the situation and both shall prevent the organization, assistance or encouragement of any acts detrimental to the maintenance of peace and harmonious relations.
(ii) In Jammu and Kashmir, the line of control resulting from the ceasefire of December 17, 1971, shall be respected by both sides without prejudice to the recognized position of either side. Neither side shall seek to alter it unilaterally, irrespective of mutual differences and legal interpretations. Both sides further undertake to refrain from the threat or the use of force in violation of this line.
India has no grounds to complain about Kargil, given her own unprovoked hostile acts in Siachen. If anything, Pakistan's Kargil action was a reaction to India's Siachen hostilities.