It is extremely risky to fight a war on two fronts, but both fronts are contrasting.
The eastern front is made up of LOC, working boundary and International border. This front has war bells of of conventional warfare for which the majority of Pakistan Army, PAF, and PN are poised against India. The two strike Corps, and then 5th, 30th as well as 31st Corps are the maneuver Corps which have armored and mechanized formations. The terrain in Punjab and Sindh also supports gunship operations as backup for ground forces. PAF has all their major AFBs in these regions and the bulk of PAF's strike aircraft are stationed here. PAF F-16s are permanently stationed in Punjab and Sindh, the J-10s along with Mirages are stationed in Punjab for strikes towards IOK, Indian Punjab and southeast direction towards Jaisalmer in the desert.
The LOC is a heavily defended area, which can turn volatile in minutes as there are many LOC violations on regular basis from India. When Indian troops in IOK fire at AJK, PA gives a befitting response, so India loses a few soldiers to kill a few on Pakistani side. This isn't working well for India. The working boundary at Sialkot has firing incidents but are rare. Even then both these "demarcations" are backed up with conventional infantry, artillery and armored formations. The IB from Lahore to Badin is patrolled regularly by Rangers on pakistan side and BSF on Indian side. That leaves two more regions: Siachen in north and Rann of Kutch in south. Siachen is an extreme example of LOC- all the offensives of 80s and 90s don't occur anymore, both sides know they will lose troops to enemy fire while the troops are already battling -50'C weather on both sides. The Rann of Kutch is being defended by three forces from three sides by three forces - Army from north, Rangers from west and Marines from south, where the creek area ends. India is angling towards creating a new issue in Rann of Kutch.
This is why a conventional war on eastern front is NOT favored by India, as India hardly gets the advantage it wants.
Now, the western front is another story. This was a low priority border for Pakistan except in 80's. In 2000s, it has gained momentum in unconventional warfare and this is where India wants to defeat Pakistan. Early on, PA shifted reserve formations of Strike Corps, especially 14th ID from II Strike Corps and 17th ID from 1 Strike Corps to Swat and FATA regions. That made Indians very happy, which ended in the 2001-2 fiasco where India lost troops bringing them towards the border. Pakistan told Uncle Sam look what our naughty neighbor is doing and Uncle Sam sitting in Afghanistan told India to back off, as they were getting assistance from Pakistan to target AQ.
Thus later on, Pakistan raised two more FC formations, one in KPK and one in Baluchistan. This angered the Indians as now Pakistan won't be moving its forces towards west from east. Furthermore, Pakistan started FC in CT and COIN ops with upgraded weaponry, vehicles and communication systems. Later Pakistan formed CTD to help Police all over Pakistan against TTP and BLA.
There was one defective side though, the AH-1 Cobras couldn't perform ops in high altitude areas like ParaChinar so Pakistan chose AH-1Z, then T-129 and now Z-10, but by this time the nature of warfare had changed again. India now wanted Pakistan to lose soldiers on western border without directly involving Indian troops unlike LOC, so TTP was funded. If you calculate, for one terrorism incident by TTP, India spends roughly USD ~40-50,000. Thats a huge cost if you multiply it by incidents in a year. That is why the annual budget of ISI is peanuts compared to RAW.
In this recent Afghan-Pak war, it was FC fighting on all fronts, the regular Army was back up incase FC falls back, but that never happened. The Afghan border posts were also captured by FC, not PA or SSG. So Pakistan's plan worked regarding FC as a fighting formation in conventional and unconventional warfare. Somethings that Rangers aren't even exposed to on the eastern border. This is why FC was given Type-69 tanks and 25-pounder howitzers (WWII era) along with RPGs, mortars, etc.
This shows that in an event of war where India and Afghanistan attack Pakistan simultaneously, the advantage that India thought it could have has been nullified to a great extent. PA on eastern border can thrash Indian Army while FC on western border can thrash Afghan Taliban and TTP.
The terrain on western border is a very big challenge. PA needs lots of helis, lots of secure bases and posts. The mountain region is treacherous for transport by road or on dirt tracks unlike LOC. The LOC has lots of vegetation (trees etc), where as western mountains are bare and rocky. Patrolling becomes an issue. Even communication becomes an issue, its not easy for transmission signals to pass through rocks and inside caves. Taliban have been using Thuraya satcom phones since 2000s, but they have limitations also. If FC gets smaller fennecs for patrolling or QRF then that would be helpful otherwise traversing on vehicles is limited in mountains.
Now, the Durand line itself is an issue. Afghans and Indians want it to remain an invisible line, not a International border. So a diplomatic front in Qatar needs to be opened to ensure that everyone recognizes it as a border, otherwise no one will adhere to international laws or agreements terming the line isn't a border.
TTP claims KPK as their land, Taliban wants to lay the same claim too. There is religious extremism which drives human resources from Pakistan tribal areas (KPK and Baluch) and Afghanistan to join TTP and BLA (missing persons saga). This recruiting drive has to end. Any military force has a budget and can sustain a certain number of troops. This isnt applicable on terrorist outfits. They can instantly swell in numbers and then go thin as sides are changed. Pakistan is killing disgruntled, then religiously brainwashed Pakistanis (Afghan mixed family) and Afghanis and lastly vengeful Afghanis who cant bear the fact they have beaten superpowers but cant beat Pakistan.
This is why this war on western border has no end in sight.
The major challenge in every war is technology. Firstly, the one with cutting edge systems will have an upper hand and secondly how can the use of such technology bring success in unconventional warfare like western border.