This is saying good morning to everyone at midnight levels of pedantic. Astronomers need a common reference frame for discussing timing, and the reference frame they use is "when it's observed at Earth".

Because nothing else allows for coherent organization, discussion, or education.

A nuclear fusion event occurred in the accretion disk of a stellar remnant 2600 years ago or so. An astronomical event known as a nova will occur in the sky sometime this summer.

Read up on reference frames.

Discussing astronomical events would be incredibly tedious if we had to qualify everything by how many light years away / how long ago the light we’re measuring was created.

Put another way - everyone already knows we’re looking at the past, it’s like saying the sky is blue.

Our receipt of the photons is what we're concerned with, and that has indeed been years in the making.

You must be really fun at parties.

a very, very long time ago

Some precision here would be appreciated

Years in the making is correct. Whether it's 5 years or 5 billion years, that's years in the making.