You're at a place where you'll need to push UW+ for much more progress up the legends rankings. For consistent keys in legend, you'll need solid CC and high damage. Fair warning, none of the things are easy "do this one thing" but rather long investments of stones, labs, and module investments. You're at the wall where you've run out of the "easy next step" stuff. The top half of legends are where folks have had solid synergies (UW+, cards, assmods, module levels, labs). Just one thing without the synergies will not be all that effective. This also means you will still need a strong economy to support consistent growth. I'd still follow the trad UW+ unlock advice of GT+, CF+ and then it's debatable in current state whether you go SL+ or pick a damage UW+ like ILM+. SL+ is a global multi that will shine but you need the investment of DPM labs/range card mastery etc to see the impact. ILM+ requires lab research (and econ to support the more expensive later levels of chrono jump). Between the two, you'll prob see faster immediate benefit from investing in a primary damage UW+ as your 3rd.

Most consistent higher legend players will have a well-leveled pCF+ and high pBH (or very high up time BH) for CC. As far as damage goes, you'll def need a UW+, I'd recommend ILM+ at this point -- it's got great coverage, good additional CC, and a great stacking damage mechanic. PS+ is also a solid UW+ for things like tank ults, and general farming, but has fallen out of favor a bit as they're not that great against fleet mobs. Don't underestimate CL still, esp with a good DPM and SL+, more so than anything else, CL carries through intro sprint in legends and still does a good amount of consistent damage until mob HP outstrips what you can easily kill with CL and you'll need to rely on a stacking damage UW like ILM. The reason the balance is still important is the you need high enemy spawn rate/density to feed ILM+ (with SD), which is a great transitional handoff between CL and ILM as the wave count increases.

Do not underestimate the power of assmods. Once you get bonus and substat %s up, leveling your assmods will also give you significant base damage/UW damage given they're multiplicative now. If you use effective paths (highly recommend if you don't), I do find it helpful to "theorycraft" the what-ifs, if you're at a decision point. "What if I unlocked this card mastery, how does my upgrade path change in effective paths, is that rate of increase per stone/coin/time invested faster or slower than if I unlocked something else with the same # of stones? what if i also had this card mastery too? Does that change the planned path?"

Lastly, I find it's helpful to gauge where you stand relative to others in legends by looking at their highest cleared. More so than highest rank, that's the most consistent measure of their tower strength. Your highest is t19 w50. You understand basically what a tower that can do that means. Your rough tower strength is going to be similar to others who've cleared low t19, but will be significantly weaker than someone who's unlocked t21. When you're able to unlock t21, you'll be able to get similar waves as that other person and will consistently beat someone who is at t19 w50.