There's a lot there, so a few points to keep it simple:
What you're describing are non-cashable flex credits run through a Section 125 cafeteria plan.
Only Section 125 qualified benefits can be allocated through flex credits.
HRAs are not a Section 125 qualified benefit. An HRA cannot be funded directly or indirectly by a cafeteria plan.
ALEs need to make sure there are sufficient flex credits that qualify as a "health flex contribution" to ensure the plan meets the ACA affordability test.
Flex credits that can be allocated to the health FSA generally need to be cashable to avoid losing excepted benefit status.
Only cashable flex credits can be allocated to the 401(k).
For a list of qualified benefits, see slide 6 here: 2021 ABD Section 125 Cafeteria Plans Guide
For an overview of flex credit issues, see here: https://www.theabdteam.com/blog/how-aca-affects-flex-credits-2/
Here's a "health flex contribution" overview:
https://www.theabdteam.com/blog/how-the-aca-affordability-increase-to-9-83-affects-employers/
How Do Flex Credits Affect the Affordability Determination?
Flex credits will reduce the dollar amount of the employee-share of the cheapest plan option providing minimum value that is used to determine affordability if they meet a three-part test to qualify as a “health flex contribution”:
The employee may not opt to receive the amount as a taxable benefit (i.e., it is not a cashable flex credit);
The employee may use the amount to pay for minimum essential coverage (i.e., the employer’s major medical plan); and
The employee may use the amount exclusively for medical/dental/vision coverage costs.
Action Item: If you offer a defined contribution-style flex credit approach to employees, make sure that a sufficient portion are designated as “health flex contributions” to qualify under an affordability safe harbor. This will require at least some of the flex credits be non-cashable and designated for health plan purposes only.
Here's the guidance prohibiting any interaction between the cafeteria plan (including flex credits) and HRA funding:
IRS Notice 2002-45:
https://www.irs.gov/pub/irs-drop/n-02-45.pdf
IV. HRAs and Cafeteria Plans
Employer contributions to an HRA may not be attributable to salary reduction or otherwise provided under a § 125 cafeteria plan. An accident or health plan funded pursuant to salary reduction is not an HRA and is subject to the rules under § 125.
...
An arrangement is not treated as an HRA if the arrangement interacts with a cafeteria plan in such a way as to permit employees to use salary reduction indirectly to fund the HRA. Therefore, where an employee who participates in a reimbursement arrangement has a choice among two or more specified accident or health plans to be used in conjunction with the reimbursement arrangement (or a choice among various maximum reimbursement amounts credited for a coverage period) and there is a correlation between the maximum reimbursement amount available under the HRA for the coverage period (disregarding amounts carried forward from previous coverage periods) and the amount of salary reduction election for the specified accident and health plan, then the salary reduction is attributed to the reimbursement arrangement even if the amount of salary reduction election is equal to or less than the actual cost of the other accident or health coverage.