Your build is really solid, and your replacements look good come lategame. I feel like Runeglaive is definitely stronger for her early game burst, but Cinderhulk works well if you are going to be a tank come lategame.
I usually build very similarly on Elise. I either buy Runeglaive straight up as a first item, or I buy a Haunting Guise first item and build into Cinderhulk (this is the build I would use before her 5.14 buffs, when I would max q-->e-->w). Next I would either get an Abyssal or a Frozen Heart depending on the enemy team comp and who had the majority of the farm/kills on the enemy team. Frozen Heart is a really good item on Elise as it does give you the double damage from Liandry's with its aura and she likes some CDR come lategame. Boots are up to the player and the team you are up against (high CC = mercs). Depending on the situation, you can opt to go for more damage in your build or go more defensive. Always take into consideration the runes you are running too, as sometimes I run CDR/lvl and in these situations, I would either build Cinderhulk or not buy Frozen Heart if going Runeglaive (opting for Randuins as an armor option). Rylai's is a good offensive option in conjunction with Liandry's as they work really well together and it adds a little extra CC to your kit. If you get Cinderhulk, this item combo is even better due to the amount of health you will have.
As far as resistances go, I feel like you don't really need to prioritize armor on Elise early unless the AD's are fed, or you are facing a mostly AD team (magic damage coming mostly from tanks/supports). Due to AD damage usually being over a longer period of time, you can sustain through this damage a lot better as Elise with her on hit healing. You should be looking to survive burst damage as Elise though as she is really squishy and can be bursted down rather easily. Building a lot of health and prioritizing MR should help you here. For this reason, I'm a fan of the major MR/Health items on Elise such as Spirit Visage (mostly for CDR needs), Banshee's (great for most situations), and Aegis (if your team needs one).
The one criticism I might have with your build is that Abyssal may have been built a little late though that is not guaranteed as I don't know how soon you got the item. Abyssal is best when bought very early before enemies have considerable MR, but it is still a good buy to amplify your damage while also reducing magic damage. Given 3 of their heaviest damage dealers were AD (though Ekko did the most damage on the enemy team), armor may have been more of a priority, Randuin's probably being the best option for mixed damage (considering they had Ezreal). Diana also built Abyssal and the auras don't stack, so keep that in mind as well. You were in a tricky situation as your full team was magic damage, and you were the most fed on your team. Elise isn't really the best at being the main carry on a team because she doesn't scale so well into the lategame. I would say you did a good job for what you were given. Build wise, it's solid. I don't personally like finishing Liandry's right away, but I think that might just be an old habit as it does give considerably more AP now than it did before.
I have quite a few builds that work in different situations. I usually run AP quints, AS marks, HP/lvl seals, and either CDR/lvl or AP glyphs (if I plan on going Runeglaive, I will opt for CDR as I will be getting the AP soon and CDR is harder for her to get when going offensively). Elise is one of the only junglers that can go without armor runes while jungling so I opt for HP/lvl as it scales better with Cinderhulk than 9 armor. AP and AS runes are pretty standard for AP junglers. Note: I almost always go Stalker's unless the enemy team is full of tanks.
Item builds (Runeglaive):
(finish Liandry's) + armor item. {Optimal build}.
Finish Liandry's
+ AP, Health, or additional armor item {Full AD enemy team}.
Finish Liandry's
{great against high Magic damage or high CC}.
(Cinderhulk) --I honestly feel it gives you more options as you don't feel obligated to build more offensively; I always go Haunting Guise before finishing Cinderhulk, so keep that in mind after the first example:
finish Cinderhulk
finish Liandry's
{great tanking + good damage}.
{vs Magic damage optimization}.
{damage heavy + less tanking potential; survive the initial burst}.
Items that can be swapped in easily, but weren't in the examples:
(runeglaive only).
Items I don't personally like:
(unless swapping Sorc boots)
