The CTM add-on is an add-on that brings connected textures to Vanillaccurate. It’s available in various resolutions to match the main pack’s.
The CTM pack brings connected glass and might bring stuff like connected quartz, bookshelves, sandstone...…

This Biomes’o’Plenty add-on brings the Vanillaccurate style to the new blocks the Biomes’o’Plenty mod offers.

You’ll find a quick tutorial here.
In most cases you don’t need the converter at all, you’ll find all you could need in the download pages.

These scripts allow you to upscale default Minecraft resourcepacks to your desired resolution.
This is useful for shaders like SEUS PTGI that requires all blocks to be the same resolution for POM and reflections to work.
If you have an incomplete pack and notice issues on missing blocks (falling back to vanilla textures), then use these.