A Metro Council member today revealed the existence of a previous appraisal of the Metro-owned park at the center of a controversial land swap, one that puts a higher value on the land than an appraisal that was released earlier this month. The previously undisclosed appraisal, which is dated Sept. 28, values the Church Street Park land at $5.47 million, were it to be developed into a high-rise, as developer Tony Giarratana intends to do, if the swap is approved. That appraisal is nearly $1 million…