Does there exist any BIOS for any 5-Volt-only 486 motherboard that can display the CPU frequency of a 486 processor past 100 MHz correctly?
I refer to modern 3.3 Volt 486 processors like the Am486DX4 or Am5x86-133 that are placed via an interposer into such an old board then.
First I'd say, I'd be happy if I could get such an old processor to run at all in such a mainboard.

The next thing is, I won't expect this board to support a key feature like Write Back cache of that too modern processor.
With introduction of higher clock multipliers (3x, 4x) it became more and more a performance issue to support L1 cache in write back mode.
Cyrix was the first manufacturer to include a write back cache in a 486; it starts with the Cx486 DX.
I'm not sure whether Intel has revealed their write back plans first with the Pentium Overdrive enhancement or the enhanced DX4, however the layout of course was different to the Cyrix implementation.
To set the clock multiplicator, there also exist 2 standards - for example my Am486DX4-NV8T/100 requires another jumper block than my Am486DX4-SV8B/100.
So this is a result why wiring and jumper setting became a nightmare on later 486 boards.

I've seen that Digital Venturis posted in 3 other threads. It seems like it won't display past 100 MHz.
Also my 486 EISA-AE4 won't display that fast speed.
However, they run at full speed.
I won't call this a BIOS fault. And I'm sure I won't get a BIOS update for both boards.
And it seems like both boards support 486 CPUs in write through mode only.

More thoughts:
In the contrary, I've also made the experience that my Intel Saturn II based ASUS PCI/I-486SP3G does support the Am486DX4-NV8T/100 but it refuses to boot with either Am486DX4-SV8B or Am5x86. (It is capable to run 3.3 V processors tough!)

In SCSI (Wide SCSI EISA) and network performance (100 MBit/s EISA) the benefits from an write through Am5x86 clocked at 3x50 have been so low compared to my Intel 486DX 50, so went back to the contemporary CPU there.

Is there any comparable situation after the 486's? I'd say yes.
When you install a modern Ryzen into an AM4 board, it probably may not boot at all. Upon request AMD lends you an old AM4 Athlon to temporarily install it just to do the BIOS update and to send it back later.
I also noticed that first 100 MHz Pentium 2 mainboards had stability issues when running a Deschutes core - before doing a BIOS update.