Faithlife has already created a powerful tool in the Catholic Topical Index, which, as far as I know, is only available through Verbum base packages and crossgrades. My suggestion is to create something similar for Logos for Protestants, but to expand the topics included as much as possible, remove the references to Catholic sources (Vatican documents, encyclicals, etc.), and have it strictly reference the Church Fathers. It would be used within the Topic Guide or Factbook, somewhat akin to the Ancient Literature section in the Passage Guide. Rather than showing references to the Fathers by passage, it would do so by topic. Since I do not own the Catholic Topical Index, I cite the entry for "Baptism" from the index J.N.D. Kelly's Early Christian Doctrines as an example of what I have in mind:
Baptism: teaching of Ambrose, 355, 422, 423, 430, 432; Ambrosiaster, 356, 432; Athanasius, 427, 430, 431; Augustine, 364–6, 423, 425, 427 f., 429 f., 431, 432; ‘Barnabas’, 194; Basil Caes., 427; Chrysostom, 405, 430, 431; Clement Alex., 207, 318; Clement Rom., 194; Cyprian, 176, 206, 210 f.; Cyril Hieros., 423, 425, 427, 428 f.; De rebaptismate, 210; Didache, 89; Didascalia Apostolorum, 219; Didymus, 427, 429, 431; Eusebius, 427; Gregory Naz., 425, 430; Gregory Nyss., 431; Hermas, 194; Hilary, 409, 432; Hippolytus, 208; Ignatius, 194; Irenaeus, 195; Jerome, 429, 430; Justin, 33, 89 f., 194 f.; Novatian, 209 f.; Optatus, 411, 424, 429; Orange, council of, 372; Origen, 208; Pelagius, 359, 366, 430; Pope Stephen, 210; Tertullian, 39, 209; Theodore Mops., 403, 430–2; Theophilus, 195; Zosimus, 370
https://www.logos.com/product/34092/j-n-d-kellys-early-christian-doctrines-and-creeds
Kelly's page numbers refer back to his own book, but what I envision would link directly to the Patristic sources, assuming they are available in one's library.
Looking at the BIG picture, this would just be a starting point. The Index could eventually be expanded to include results from all (or at least most) of the works included in the Ancient Literature section of the Passage Guide.