Since the publication of my last post, I have gained some new insight into the Coptic Psalter Codex sa 2033, which I am sharing below. 

1. Following a valuable hint given to me by Professor Rainer Stichel,[1] I consulted the series of Psalm titles written by Eusebius of Caesarea around 330 AD [2] and reproduced by Jacques-Paul Migne [3] under the heading Υποθεσεις του αυτου ευσεβιου εισ τουσ ψαλμουσ. As noted by Martin Wallraff, it is “a shortlist by Eusebius of the subject matter of each of the 150 Psalms”.[4] This shortlist precedes the Psalms in the famous fifth century manuscript Royal MS 1 D VII known as Codex Alexandrinus preserved in the British Library in London.[5] 
It turns out that the headings appearing in the Coptic Psalter sa 2033 are a quite literal translation of the Eusebian Psalm titles. Let me illustrate this with the titles preceding Psalms 64 and 65; the table below is followed by a detail of the manuscript showing the beginning of Psalm 64. 

Detail of Berlin, SBB, Ms. or. Fol. 1605, f. 3r. http://resolver.staatsbibliothek-berlin.de/SBB0001C5A400000017 (Licence: CC BY-NC-SA 3.0 DE)

I checked each of the Psalm titles extant in sa 2033 and was able to ascertain that the Sahidic titles correspond to the Eusebian ones except for the titles of Psalms 146 and 148 (coincidentally being those reproduced in my previous post). I have now found out that these two titles appear in Latin in several manuscripts and belong to what Pierre Salmon calls the first series or “Série de Saint Colomba”. The Christian titles of this series are widely attested in Europe as early as the sixth century “quelles que soient ses origines plus lointaines”.[6] The fact that they appear in our Sahidic manuscript suggests that their origin must certainly be Greek. In a longer article I am currently working on I will give the complete comparison between the Eusebian tituli Psalmorum and those appearing in sa 2033.

2. Searching through the Göttingen VMR for other Coptic witnesses of the Eusebian tituli Psalmorum, I discovered that two London fragments classified by Karlheinz Schüssler as a codex of their own with the siglum sa 185 [7] actually belong to sa 2033 (BC sa 101). The London fragments in question are 

• London, BL, Or. 6954 (96), a fragment complementing Cairo, CM, Inv. no. 3854 bearing Ps 24:7–15; 25:1–9, and
• London, BL, Or. 6954 (98), a fragment bearing Ps 67: 21–26; 68: 1–5 to be placed between Berlin, SBB, Ms. or. fol. 1605, f. 3 and Paris, BnF, Copte 133(2), f. 26b. 

The new fragments also contain the Eusebian tituli Psalmorum, and this brings the identified parts of sa 2033 to 26 fragmentary folios dispersed among 7 libraries. All 26 leaves are now freely available in the Göttingen VMR in the correct order with the indication of their content.

[1] Rainer Stichel is the author of the book Beiträge zur frühen Geschichte des Psalters und zur Wirkungsgeschichte der Psalmen. Paderborn et al.: Verlag Ferdinand Schöningh, 2007. Also see his article Zur Herkunft der Psalmenüberschriften in der Septuaginta, in: Erich Zenger (ed.), Der Septuaginta Psalter. Sprachliche und theologische Aspekte. Freiburg et al.: Herder, 2001, 149–161.
[2] On the possible date Eusebius of Caesarea (also called Eusebius Pamphili) wrote his hypotheseis, cf. William Smith and Henry Wace, A Dictionary of Christian Biography, Literature, Sects and Doctrines. London: Little, Brown and Company, 1880, 308–355 at p. 336–337.
[3] Migne, PG 23: 68–72.
[4] Martin Wallraff, The Canon Tables of the Psalms, An Unknown Work of Eusebius of Caesarea, in: Dumbarton Oaks Papers 67 (2013), 1–14, 9. As for the number of 150, note that all witnesses of Eusebian Psalm titles refer to 150 Psalms following the Masoretic tradition (unlike the LXX, which has 151 Psalms). The Latin translation of the Eusebian Psalm titles constitutes the Série IV in Pierre Salmon, Les “Tituli Psalmorum” des manuscrits latins, Collectanea Biblica Latina XII. Rome: Abbaye Saint-Jérôme and Libreria Vaticana, 1959, 117–131.
[5] See fols. 531v–532v in The Codex Alexandrinus in reduced photographic facsimile, The Old Testament, part IV, published by the Trustees of the British Museum in 1957. It also features in other Greek Psalm manuscripts and Catenae. Some examples are Oxford, BL, MS. Auct. D. 4.1, f. 26r–28v (10th century), and Rome, BAV, Reg. Gr. 1, f. 488v–490r (10th century). More examples and a discussion can be found in Cordula Bandt, Eusebius Periochae, in: Cordula Bandt, Franz Xaver Risch and Barbara Villani (eds), Die Prologtexte zu den Psalmen von Origenes und Eusebius, Texte und Untersuchungen zur altchristlichen Literatur 183. Berlin/Boston: De Gruyter, 2019, 122–141.
[6] Salmon, Tituli, 47.
[7] Karlheinz Schüssler, Das sahidische Alte und Neue Testament, Biblia Coptica 2.2. Wiesbaden: Harrassowitz, 2015, 17–18, sa 185.