Do most native speakers understand these Chengyus at all? 霽範永存, 亹亹不卷, 巾袖無光, 鑿枘不入
I would like to say they are uncommon variants of common 成语 or just single case originated from some literature, which I think I am inventing such 成语 everyday. But it requires high level of classical Chinese skills to recognize.

Here I would show what I thought before I search for more info.

霁范永存

身正为范。范乃楷模之意。

又，光风霁月。霁乃晴明之意。

又，正气永存。

So I guess it means:  高节永为世人之楷模。

After searching: Exactly as what I thought.

亹亹不卷

亹亹文王，令闻不已！

勉励的文王啊，他的美名没有止尽。

又，孜孜不倦。

So I guess 卷 is the ancient variant (or origin?) of 倦. So this 成语 means 勤勉而不知疲倦.

After searching: 今作：娓娓不倦，多指谈话娓娓不绝，不知疲倦。

巾袖无光

巾，手帕。袖，衣袖。

又，黯淡无光。

不考虑比喻，似乎就是：衣服不起眼，或陈旧。不能推断意象。

After searching:形容穿戴的服装敝旧不华丽。孤例。

凿枘不入

This is obvious~

方枘圆凿。

They are the same.

After searching: Yes!

P.S.

It is not any four-character, concise word that can be categorized as 成语! A 成语 should be popular enough (at least in its time)!

彼素苑囿籍典，兀兀以穷；今闻鱼跃之喜，定不自胜，故延亲邀友，飨于庭园。倾以仪狄，馔以凤肝，奏以焦尾，焚以龙涎，欢歌笑语，春风踌躇。

See? I use A LOT OF four-character verse, but they are (mostly) not 成语, but my personal invention.