'expertly-installed' is a compound formed from the adverb 'expertly' (itself from the adjective 'expert' + suffix '-ly') and the verb 'install'. 'Expert' originates from Latin 'expertus' meaning 'experienced', and 'install' comes via Old French/Medieval Latin from Latin roots meaning 'to place or set up'.

'expert' comes from Latin 'expertus' (via Old French and Middle English) meaning 'experienced'; 'install' comes from Old French 'installer' and Medieval Latin 'installare' (from Latin elements meaning 'in' + 'stall'/'place'). The combination into a hyphenated compound adjective (expertly-installed) is a Modern English formation used to describe the manner in which something was installed.

Individually, 'expert' originally meant 'experienced' and 'install' meant 'to place or set up'; combined, the compound came to mean 'placed or set up by someone experienced' — essentially the same core idea expressed as a compound adjective.