Not the OP, but, I'm also hyperphantasic, which is the name for that. For me, personally, I usually think in something akin to visuals, but, with all the other qualia mixed in as relevant, not just visuals.

Quantity is not necessarily a problem: it feels a lot like the same tradeoff as if you need to picture a lot of apples in an image of fixed resolution, you can make them smaller/less detailed just by, loosely, "allocating fewer pixels per apple", rather than needing the same detail for each that you'd need if you're trying to zoom in depth into one apple.

However, if I have a situation where I have to picture a lot of very detailed things of irreducible complexity (the details matter) that need to be placed in a specific configuration (the ordering matters), then it gets harder. Statistics was so intuitive for me that I would read the equations as visual images in my head because it was throwing out the individual details and dealing with population mechanics as individual objects of study. However, combinatorics was initially very hard for me to learn because it was dealing with very large numbers of hierarchies of orders as well as the specifics of their interrelations, so building intuitive understandings of why the theorems were correct was very difficult.

I have learned to lean on a very internally barebones representation of language/symbolic structures when needing to reason about certain complex topics that require it, but, even then, often when I'm conscious of it, it's almost like I'm visualizing the letters or forming the words as sound in my head. When I'm forming sentences to actually speak or write, it feels like I've got a concept that I've turned into a "rendering" that I'm trying to communicate via language substructures. To do so, I'll break it down into component parts and just start describing the substructures as if I'm perceiving it and describing it live in small parts. It feels like the learned skill required for speaking a language for me is learning how to decompose and reorder these objects into chunks that are expressible within the vocabulary and grammar of the target language and finding the correct words&patterns that represent and order these chunks most efficiently for effective communication. Almost feels like a SAT problem or a language diffusive process (and likely is, to some degree, related to those processes or similar under the hood), but, it actually qualitatively feels that way to me, consciously/experientially. Language feels almost bolted onto my experience rather than the primary mode of thought, even if I can think in it if needed.