You specifically mention old software, but for older software Wine on Linux seemed very reliable to me, probably because older interfaces are better tested already. Some very old games (i.e. Win 95-XP era) worked better for me on Wine than on modern Windows out of the box.
DXVK definitely made all the unoptimized older games easier to run, compared to running them natively on Windows.
You specifically mention old software, but for older software Wine on Linux seemed very reliable to me, probably because older interfaces are better tested already. Some very old games (i.e. Win 95-XP era) worked better for me on Wine than on modern Windows out of the box.
DXVK definitely made all the unoptimized older games easier to run, compared to running them natively on Windows.