I would cut that leaf down by half, following the natural shape of the leaf. I would give the leaf portion a shower every day in case it's bugs. Have you allowed the soil to dry too much between waterings? What size is that clay pot that it's in? Can you take pictures of it from different angles including the pot and inside the pot? Edit: I'm going to take a picture of what I mean when cutting. This is Philodendron hederaceum. I cut leaves sometimes when propagating vines if it looks like the leafs are transpiring too much and causing it to be unable to root. (Sign of this is when the leaves are constantly wilted)

Yes, a node is the bud, the bump which is usually just above the line which divides sections of the stem. In your marked picture, you've indicated the brown section division line as a node rather than the bud, which isn't correct. You did identify a bud, which IS a node. Once a node breaks and produces a new growth, it can't regenerate again if the growth dies. If that growth dies but not all the way back to the parent stem, there could be a node that could grow. This is what has happened on your stem sections 4 and 5. So look for the nodes, the bumps on the stem, rather than stem sections. The node you cut into is high and obvious, sometimes they're flat with only an encircling indentation to show you where they are. I'm not of the opinion that cutting a stem with a node away from the parent plant will encourage it to grow. By doing that you cut off energy the main stem is providing to that stem sections with the node, making it weaker. You also introduce an open wound where rot could start. So there's no benefit by cutting in my opinion and I would leave everything alone, just be patient. It will grow whenever it's ready, it might even wait until spring. It's possible node 3 could grow, it hasn't turned black so that's a good sign. I suppose it depends on where the cut is on the node, hopefully it's on one side or the other of the microscopic tissue where growth comes from. There's a node between where you indicated Node 1 and Node 2. The node, the bump, should be just above the lower brown ring. I can't tell which way the short stem with Node 4 and 5 is growing, but there is a node in the section that comes off the main stem. The next section attached to it that terminates with a cut may or may not have a node. Looking carefully with a magnifying glass for the bumps might tell you. On watering, if you can't tell for sure if the medium is damp then it's pretty dry and I'd go ahead and water. These are tropical plants and don't like being completely dry at the roots.

I didn't even think to mention that you could spray the leaf with water in order to help lubricate it first. That would've probably made things easier. It doesn't look that bad, and there'll be many more leaves where that came from. Just keep it flushed out with plenty of water and you shouldn't have any more problems like this. You wouldn't even have to mist them either. I never mist mine. Just in the case of this unopened leaf would it have come in handy. It's only when Aroids are kept too dry that their newly emerging leaves get stuck like this.

could we have a pic of the whole plant ... it is not uncommon for plants to lose the oldest leaves in fall or winter ... and then new ones start growing ... if thats the case.. you just cut off the older ones that look like heck ... some of it looks like what we call mechanical damage ... something hit it.. or bammed it.. or something or another ... i see you linked CA gardening ... it always helps us if you tell us where you are.. big city name ... is this outdoors.. or recently brought indoors... etc ... a little more history of what this plant has gone thru in the last 6 months might help ... did you maybe move and jostle it around.. etc ... lets see the whole plant ... and see if we can come up with some ideas ... but i dont see much of anything in these pix.. to really worry about .. ken