The last time we were at MK, the HM cue was terribly dark. It felt unsafe with my elderly mom with cognitive issues. I broke out my cell phone flashlight and got fussed at by the CM but I honestly didn't know what else to do at that point.
Its understandable that you would try to light your own way like you did, but the main problem with doing that is that if you do not keep the phone light directed
only at the floor, and it shines upward *
at all* it can effectively blind someone else who is struggling to see in the poor light. I have low vision in dim situations, but it is 10x worse if a bright light is “flashed” at me. I was blinded more than once by a flash photo being taken by someone in a queue or on a ride (despite the warnings*

). After that, my low vision effectively becomes NO vision for up to several minutes.
*I even did it to myself once on HM at the mirrors at the end of the ride… many years ago now, I had my spanking-new iPhone, back when the flash on the camera was a new feature.… I just wanted to get a quick shot of the ghosts in our doombuggies (this was also before they had the ride photos). I forgot about the automatic flash feature.
So not only did I not get the photo(s), I ended up blinding *myself* and could barely get off the ride. DH had to tell them to stop the walkway, and then lead me off while trying to herd our monkeys, er, boys off the ride as well. I felt like a complete idiot..
In the future, I suggest you take your loved one by the hand and stand still or step to the side of the group. Then when the CM comes along to “bring up the rear” tell them you are unable to see well and that in the low light, you do not feel safe to move from where you are standing. Be specific that it‘s a safety issue. They all carry small flashlights that they can use to illuminate the path forward. They will assist you and hand you off to the next CM in the queue. We’ve done this at DL in HM & at least one other ride (although which other one it was I cannot remember right now… it’ll come to me, and I’ll edit this part

)
Another tip: when you are with someone slower or vulnerable or with whom you worry about becoming separated— as you are entering or exiting a pre-show area of the queue, allow most of the guests to move forward (or to move past you) before taking your place at the end of the bunch. Let everyone else push and shuffle for position… the extra couple minutes your party may wait to board the ride, will be worth avoiding the stress of trying to keep track of everyone as you struggle to stay together.
For some reason, this was the hardest “trick” for my family to do consistently on this last trip. It’s just habit or maybe natural instinct to go with the flow of people when they start moving. I’d take about 10-15 seconds before starting to creep ahead slowly so others would go around me, but more often than not, I ended up separated from the rest of my party, because they had just moved with the pack, and then they had to stop and let others go past until I caught up to them... Even when I reminded them of the plan as we entered the queue, like 80-90% of the time we’d have the same problem. You’d think they’d get better at it after a few times…

When we did manage to all hold back, it was so much less stress because we could stay together so much easier. Even when the next batch of guests came along behind us, we were generally almost to the point of loading, so it was rare that we had any issues at that point.