Methinks West's translation of client ('e.g. the government agency hiring a *contractor*)- oddly missing from the ProZ glossaries and IATE database - works well in this context.

El contratante in SPA and le contractant in FRE are often false friends with contractor, both often meaning the opposite as an Employer or 'Hiring Authority'.

Trying to think laterally, I disbelieve the insurance client is invariably the same as the policyholder e.g. el su(b)scritor / or, more often as as corporate policyholder*s*, la su(b)scritora, one reason being that a top-of-the-group parents may be the ins. client (insurance translators: do not say colloquially-> taking out) but effecting a contract of in. for a subsidiary that is then assigned the contract as the policyholder and party insured or - NB in marine cargo - assured.

Also cut to an AREA Helath Authority in the UK as the client taking out ins. for a specific clinic or hospital as the policyholder.

Hope it helps