Last month, the Senate Republican Caucus reported spending $22,000-plus to support Gwinnettian Garry Guan’s race for the state Senate. That would be a problem. Georgia law treats those expenditures as campaign contributions — capped at $2,400 per race. The remaining 20 grand would be illegal. Now, Republicans say that disclosure was a mistake, that the spending benefited other candidates as well. But that explanation only underscores other weaknesses in campaign finance practices.