Wow, that was hard. The only thing you will find when you search for, let's say "deutschland republikaner reaktionen", is firstly reactions to the US-Republicans, and secondly you'll find websites that are actually created by the party "Die Republikaner". There are some facts and reactions to Landtags-elections, but they are from 1986. That was around the time (as we know from the historical aspects of the party) they first appeared.
The only thing that was somehow in the news recently about the Republikaner was that they used a German comedian for their campaign in a campaign TV-spot, which was prohibited by a court shortly after it came up.
A few antifascist websites try to inform about the party, but even they somehow are not up to date about some facts.
What does that tell us about the party? Maybe that it is not important at all, maybe that you can’t take them seriously? Are there no reactions of the bigger parties on the web, because they ignore the Republikaner? I don’t know. If you have ideas – please comment!