After installing RCT1, most of the names of the coasters are;

"u(0010).td4"

etc.
I've never experienced this before, and it's a fresh install.

Searching any of the names comes up with nothing, has anyone else had this issue?

I have those. They seem to be the tracks that were included in the expansion packs; I know that the ones from the original game have the names that they shipped with. More than that I can't say.

Read the README.

User/Fan Created Tracks
*****************************
The user/fan created rides included in this game (denoted in the build window as 'u(####)' Are not
supported by Infogrames Technical Support Services.

Some User/Fan Created rides may need additional landscaping to place them in your parks

Some User/Fan Created rides may need a second track next to them to operate because
the 'Synch with Adjacent Stations' option is selected.

These aren't user-made tracks though - these are tracks included with the expansions. And when you've got fifty different variations of u(xxxx), it's hard to keep track of what you're doing.

Not true. Every track with that naming scheme is user-made.

These tracks are only on the Deluxe disc/download and were not present in Corkscrew Follies or Loopy Landscapes.