...I think I must be the only one who likes the new font.
I'll admit the change in font wasn't all that great either, I was actually quite enjoying the bitmap font with no smoothing.
If you wanna try a different font, maybe try Droid Sans?
https://fonts.google.com/specimen/Droid+Sans
Don't forget to include the license somewhere in the release, like a readme or a screen on the interface.
I tried a number of fonts, including Open Sans, Roboto but they all look terrible at that size. I also find the original fonts horrible. But given the feedback, I'll probably use the original as default, and allow you to select from one of the two. I'll see.
Maybe the odd hi-res quirks are a result of the fixes for games like Kirby's Dreamland 3, but I doubt it. It looks more like a tiling issue. I don't know what sort of games that might affect.
The mosaic effect issue is a broader issue though as a great deal of SNES games use it.
The mosaic can never be fixed as DiscostewSM mentioned. We had to sacrifice that for using the GPU to boost performance in this Snes9x port. Though, I've imagined how it would be like if we implemented some form of alternative mosaic effect...
This is all just suggestions but anything that could get the 4:3 modes sharper than they currently are would definitely help a ton.
Whether we do nearest neighbour and linear interpolation, there's no impact to performance because it's all handled by the GPU. But unfortunately, the 3DS doesn't have a pixel shader in its GPU to implement what you mentioned, so there's no way to do this in hardware.
In theory we could do what pixellate did in software, performance will suffer, and it will not be worth it.