You may be aware of this already, but there's a mod called Red Alert 3: The Third War: https://www.moddb.com/mods/red-alert-3 It's a YR to ZH conversion and pretty rough in spots, but if its creators don't mind, it may have some useful stuff for RA1 in ZH e.g. Tesla Coils and Shock Troopers, naval combat etc.

Welcome to the forums. There is no official translation into traditional Chinese for any Red Alert game as far as I know. They were never published in China. However, RA2 and RA3 are highly popular there (as you will likely know), so it is possible that someone made a fan translation at one point.

No, the world map transition only freezes with this mod. I'll give using the old files a go.

The mod looks very interesting, but the world map regularly freezes for me. The entire application does, in fact. It does recover when the animation is over, however.

Are the patches cumulative?

I see. I'll give this a shot later.

Looks great, but why not bundle this with the full game, considering that RA1 is freeware anyway?

I stand corrected.

You are the one who wants to sell some modded RA1 files here. If you have evidence that this is genuine, show it. Don't expect someone else to email random former Westwood staff and ask them about leaks.

I checked the website (Siberian Studio), but I couldn't find any download for the beta. The screenshots are probably doctored.

There's nothing surprising about this. The PSX wasn't a particularly powerful device even back in the day.

There's a a mod called Red Alert 3 Reloaded that enables the Shogun Executioner as a buildable unit. You may want to check that one out.

I played through the campaign recently. The quality is generally good, and I like the vast selection of units, but the mod seems to suffer from a common issue: Many units don't fill a niche, or fill a niche that's already occupied.

Can I switch it to a dark theme somewhere?

Welcome to the forums. To be honest, I don't think that this is worth the hassle. It's a lot of work, and there's no guarantee that the new engine would be future proof. RA2 runs fine up until Windows 7, and even getting it to run under 10 isn't that much work. Lastly, a project like this already exists: Some of the OpenRA people are working on RA2 in OpenRA.