Psalm 19/Notes/Lexical.V. 8.635627

• תורה: "In the Psalter tôrâ appears to denote God’s revelation and its promulgation, presumed to exist in either oral or written form" (TDOT). Willgren, looking at all of the uses of the phrase תורת יהוה, shows that "at least from the post-exilic period, תורת יהוה was regularly associated with a law of Moses..., sometimes specified as written," and he argues convincingly that the phrase has this meaning in Ps 1:2 (Willgren 2018, 390-1). It is probably also this meaning here in Ps 19 (so also Waltke 2010, 365). Cf. Ps. 78:5 where תורה//עֵדוּת refers to the Law given at Sinai.
• תְּמִימָה:

• SDBH notes that משיבת נפש means "literally: to bring back (one's) self; hence: = causative process by which humans or deities restore a sense of well-being to (other) humans, which may extend from feeling refreshed after a good meal to feeling contented because of a major change in one's life situation -- to restore (someone's) life." Cf. Ps. 23:3 נַפְשִׁ֥י יְשׁוֹבֵ֑ב.
• If תורה in the previous clause is associated especially with the Mosaic covenant, then עֵדוּת probably refers, specifically, to "the stipulations of the Sinai covenant laid down in writing" (HALOT 791b [HALOT, however, does not list Ps 19 under this entry]). Cf. Ps. 78:5 where תורה//עֵדוּת refers to the Law given at Sinai. Hillers argues that עֵדוּת is "actually another name for 'covenant'" and that "covenant" would be a better translation than "testimony" (Hillers 1969, 160ff; cf. NIDOTTE; so WEB: "covenant").