As a matter of interest, none of those are imports. They're all made by Legeonation. Same guy who made the Falcata and the Havoc. All five of his ships were made specifically for Disco back in the days when people around here were just first starting to learn how to texture and model ships. Texturing, in particular, took a while. Lots of trial and error.
So no, those are not imports, and no, they don't need replacing. Particularly not my Tiger Shark. D:
Now:
The Akegata should look more like what it is (that is, a transport that sacrifices cargo for combat effectiveness) rather than a giant metal pole with big cargo pod stuck to it.
Much as I hate to say it, the Waran is an import as well, and really should be remodeled. It's plain outright ugliness is its trademark, and should be maintained. It should also continue to be a solid brick of pure firepower, as that's exactly what it is.
The Rheinland Pirate Cruiser and the Vidar are also imports. Don't know anything about Rheinlandic unlawfuls, personally, but I'd think the Vidar should be remade along the lines of the Heimdall, with the RPC made to look like an old version of the Vidar.