This mod is amazing but there is some problems

The mod when in Light mod does not show Mojang logo:

Also when in dark mod the Mojang is grey instead of red.

Try delete the splash.properties file in config folder then restart the game

You can customize colours of most elements in splash.properties too, if you want red logo in dark mode

Yes, just change logoDark to 0xFFFFFF (white) or 0xEF323D (red)

Thanks, the config file was corrupt somehow by an old mod I had that had the same config name.

Anyway it works now amazing mod, can I change the Mojang Studio in the config?

Sorry I did not make a good sentence can I put my own logo instead of the Mojang Studio?

Also is there a like template of what a font file should look like?

Both logo and font can be overridden by a resource pack extracted to .minecraft/resources/ folder
Overriding the logo should place new logo to resources/modernsplash/textures/gui/title/mojang.png
Overriding the font should use resources/minecraft/textures/font/ascii.png
You can find examlpes of ascii.png by searching for font resource packs

Thanks a lot!

Minecraft\resources\assets\modernsplash\textures\gui\title work correct if it can help you