For example, if I change the unaligned move VMOVDQU to the aligned VMOVDQA, I will need another pair of macros.
You won't when keyword operand is employed:

MyVMOVDQ %MACRO DestYMM, SourceAddr, A=U
vmovdq%A %DestYMM, [%SourceAddr]
ADD %SourceAddr, 32
%ENDMACRO MyVMOVDQ

You will then write ...

Table 5‑3 shows that this works with any operation, such as `OPR R, (R)+`.
Perhaps you could add similar “syntax sugar” to your assembler as well?
I'm afraid postfix/prefix autoincrement contradict with the syntax of assemblers. Plus and Minus signs are reserved for addition and subtraction.
The ...

Release date: 2025 Nov 10
TimeStamp: 1762732800
File size: 7050396
File hash MD5: 5C2C8971A440661D3087533F76E40396
What's new:
A new program option MaxErrors= which limits the number of displayed warning and error messages with severity code above 3.
New machine instructions VPOPCNTB, VPOPCNTW ...

phpBB was updated to version 3.3.15 today.

I managed to add the new attribute RVA# into €ASM, it will be incorporated in the next release.
Although the relative address is 64 bits wide, RVA# makes it fit to DWORD variables (32 bits),
so it is useful only for SEH in 64-bit Windows. At least your example works and writes
Hello, SEH ...

.data section is now located at 0x3000 because you added constants directly to StdOutput. As a result, they were placed in the .rodata section.
This is because of literals, which are by default being put to [.rodata]. They might be placed in [.data] if you redefine the data section:
[.data ...

Relative virtual address (RVA) can be handled by preprocessing aparatus, with %SETA OFFSET# variable + RVA_of_its_section.
Offset is refined in each assembly pass until it is fixed in the final pass. Only then the linking starts and uses the RVA.
I tried to put such RVA to the section [.pdata] and ...

How to replace all these "DD 0x1044"
Perhaps instead of asm-time compute the constant at run-time? RVA already is related to %^ImageBase, perhaps something like MOV EAX, OFFSET# handler and then MOV [UNWIND + 4],EAX might do the trick?
I notice at StackOverflow that you have solved it with FASM ...

Disable warning W3410 is not a good idea, it might disalign your variables when they are mixed with shorter variables or when your program is one of modules which will be linked to PE.

Default alignment of segments built in €ASM ([.text], [.rodata], [.data], .bss]) is indeed 16 bytes only, but it ...

Yes, it will be added in the next release, in this year, I hope