No problem, I'll elaborate further on how you'll have to setup your shader for the template to behave as expected.
First you'll need to add a
Template Parameter node, and set its 'Parameter' as 'Particle Texture':
I've setup a sample shader that I'm sharing below, with the Particle Texture currently assigned to the Particle System being correctly passed to the Texture Sample, so that we can effectively manipulate it:
Note how the Vertex TexCoord is set to the 'UV Channel 1', so that we access the intended Custom Vertex Stream data that I'm sharing below:
I'm adding the custom values to the original UV coordinates, and the particles are now behaving as expected with its UVs being offset by this data:
Please let me know if this helps, thanks!