If two item sets show up for quant, I think OP might be in for a world of hurt UNLESS OP has a background in stats. CFAI can make quant questions tricky also.
I will echo others and say that you should focus on the time series reading and try to learn all the plug and chug formulas.
I didn’t wanna say it but, you said it for me lol. I worked incredibly hard on quant and still get tricked from time to time. Your statement is probably the harsh reality for someone who has skipped it at this point.
Realistically, if you read the multiple regression chapter and understand it, you don’t need to read simple regression. The only issue is CFAI might have introduced terms in the SLR chapter that aren’t redefined in the MLR chapter. I would be surprised if you’re tested more on time series than multiple regression.
I hate to say it but it may be too late in the game for you to learn quants, it takes a lot of time. You could try to read through Schweser (or another 3rd party prep provider) really quickly and then do the CFAI EOCs just learning the basics enough to maybe scrape a +50% in the section. But it typically takes videos (or visual presentation) to learn statistics well