Everything in section 7 of https://drafts.csswg.org/css-counter-styles-3/#complex-predefined-counters use custom systems in Chrome / Firefox, in order to support ranges outside of -9999 9999. We should do the same in order to pass the relevant WPT.
<rdar://problem/109875198>
> Because opinions differ on how best to represent numbers 10k or greater using the longhand CJK styles, all of the counter styles defined in this section are defined to have a range of -9999 to 9999, but implementations may support a larger range. Outside the implementation-supported range, the fallback is cjk-decimal.