Questions About Adjusting Recommendations

[UXPublishing]

I last updated my personal tools in 2022. I am refamiliarizing myself with the APCA-W3 standards to make sure I have the most up to date rules, and I am making more detailed lookup tables for each use case, font (sans) serif, font weight, and font size combo. Basically, each combination is 1 row so that there can be no confusion about how to interpret the rules. I am also trying to future proof my design system so that even if the recommendations change when WCAG 3.0 is finalized in 2027-2028, I won't have to relearn and redesign my entire system.

I have 4 Questions About Adjusting Recommendations:
Adding +15 in the APCA Contrast to Font Table Sorted by Contrast Lc Value;
Adjusting Recommendations for x-Height to Font Size Ratios other than 0.52;
Adjusting Recommendations for Serif Fonts;
Adjusting Recommendations for Different Lighting Conditions

Question 1:
I can't seem to remember how to interpret the table in the original post of this discussion #139: APCA Contrast to Font Table - Sorted by Contrast Lc Value. Beta 0.1.7 (G) Revised May 2027, 2022. For example, how do I translate this rule:
For Lc 70 and Font Weight 300:
The Font Size is listed as 28px + 15, and the APCA Contrast Legend says "To use as Block/Body Text, ADD LC15+15.
If the APCA Contrast Legend does apply to APCA Contrast to Font Table - Sorted by Contrast Lc Value, how do I interpret the rule: 28px + 15?
The APCA Contrast Legend makes sense for the APCA Font to Contrast Table - Sorted by Font Size because the cell values are Lc values. The Legend is confusing for the Sorted by Contrast Lc Values because the cells are font sizes.

Question 2:
Back in 2022, I followed the APCA instructions for How to Qualify Font Size and Weight. I used Fira Sans as the reference font so I am pretty sure my main project fonts have font weights and font sizes that are the perfectly aligned with the APCA reference fonts weights and reference x-height ratio of 0.52. I don't think I need to scale the APCA table values before applying the rules to my fonts. My main project fonts are customized Google Fonts so their x-height ratios are 0.52 to 0.54. However, most of my backup fonts like SIL fonts have smaller x-height ratios 0.44 to 0.48.
So I am not sure how to adjust the Sorted by Contrast Lc Values table for fonts that have an x-height ratio of 0.44 to 0.48. Do I just scale the Font Size cells up?

Question 3:
This table was created using sans serif fonts as a reference font. Does the following serif rule still apply? How do I adjust using the Sorted by Contrast Lc Values lookup table for serif fonts?
""Many serif fonts should use values for the row above (e.g., Times, Georgia, Cambria, Courier), and especially should be compared in terms of x-height."

Question 4:
I've reread most of the documentation but I am not sure I was able to find an answer to this question. Using the APCA method, do I need to adjust the min. font size and min. Lc values for different lighting conditions (e.g. poor lighting, sufficient lighting, and good lighting)?

Thanks for all your help! The standards are incredibly helpful. The tricky part is that there are so many rules spread out across multiple sites and pages. I just need a more straightforward set of lookup tables because there are so many rules and exceptions. It is hard to keep translate all of them in my head especially after not reviewing the rules for a long time. I'd be happy to share the spreadsheet lookup table for other people to review and use.

Here is a screenshot of my lookup tables organized by each Text Use Case. The table on the left is almost completed because the APCA documentation explained how to adjust Lc values for each different Text Use Case. The table on the right is incomplete because of some missing or confusing recommendations.