How did "trouver", which originally meant "compose", shift to mean "find"?

Question

Kindly see the embolded phrase below. How's the notion of inventing related to finding? Can you please expound this semantic shift?

troubadour [18]

A troubadour is etymologically someone who ‘finds’ – that is, ‘composes’ – songs. The word comes via French troubadour from Provençal trobador, a derivative of the verb trobar (whose modern French equivalent is trouver). This seems originally to have meant ‘compose’, and later to have shifted its semantic ground via ‘invent’ to ‘find’. It is not known for certain where it came from, but one theory traces it back via a Vulgar Latin *tropāre to Latin tropus ‘figure of speech’ (source of English trope [16]). This in turn was borrowed from Greek trópos ‘turn’, a relative of English trophy and tropic. If this is so, its ancestral meaning would be ‘use figures of speech’.

Word Origins (2005 2e) by John Ayto. p 518 Left column.

Answer 1

The etymology of trouver is not well established so the shift you mention is hypothetical.

The more common etymology (the one you found in the wiktionary) states it comes from the Latin tropus.

An interesting alternative theory by Francesco Benozzo is that trouver would come from a Celtic verb that was part of the hunting vocabulary used in Gaul.

Other hypothesis (translated from Benozzo's source) are:

1. Latin TURBARE 'to mix', with a die 'to stir' > 'to rummage' > 'to search' > 'to find' (Diez 1861, I, 427-429);
2. Latin TURBARE 'to stir [water] to direct [fish into a net]' (Schuchardt 1903);
3. Old High German TRUOPAN, TRUOBAN (cf. Gothic drôbjan, Saxon drôbhjan) 'to stir' (Braune 1894);
4. Franconian root TOP- 'to come across, to encounter' (at the origin of Castillian topar), with a metathesis similar to that found in French tremper vs. Italian temperare (Rice 1933);
5. Latin CONTROPARE 'to compare, to compose by comparing', attested in Cassiodorus and in the Visigothic laws of the 8th century. Visigothic laws of the 8th cent. (Kluyver 1909, Spitzer 1940/1941);
6. Arabic TARABA 'song' (from the root T--R-B 'to provoke emotions, to stir, to move'); the word would have entered as a loan in Andalusian Romance dialects, then in Catalan and Occitan during the period of the Arab occupation of Spain (Ribera y Tarragó 1928, II, 140-143; Menocal 1982)
7. Arabic D-R-B 'to strike, to touch' and , by extension, 'to play a musical instrument', entered Castilian before the twelfth century with reference to poets who accompanied themselves with instruments (Lemay 1966)

Sources:

• The paleolithic continuity paradigm for the origin of the Indo-European languages

• "Trouver", "trovare", "trobar": l'ipotesi celtica, 2010 (Italian)

Answer 2

Inventing and finding can be connected in meaning : inventing, creating or composing is sometimes described as finding new ideas, or finding inspiration,

Anyway, there are still other possible sources for trouver. For example, Littré cites a source tracing it from latin turbare (to disturb, to trouble) :

Il est certain que turbare a pu fournir la forme du mot ; Diez cite l'anc. portug. trovar, troubler ; le napolit. struvare, qui est le lat. disturbare, et controvare qui est le lat. conturbare ; on peut y ajouter le français truver : Es tribulations chi truverent [troublèrent] nus mult, Liber psalm. p. 61. Diez établit ainsi la série des sens : turbare, remuer, fouiller, d'où chercher, d'où trouver. Il ajoute que cette étymologie rend raison de controuver, controvare ; la préposition latine cum ne se joint pas d'ordinaire avec un verbe roman ; mais, si trouver est turbare, le mot controuver a été produit par conturbare, avec le changement de sens.

Here are the successive meanings mentioned: "trubare, to shake, to rummage, hence to search, hence to find"

(which seems to me even more audacious than the inventing-finding connection!)

source : https://www.littre.org/definition/trouver