Flowery and conceptual discourse should be kept at bay

And add to this marketing feel good latest jargon. In business settings, there are several reasons why the client should keep in mind to stay with a simple speech to be effective. Flowery language, catch-phrase laden enthusiastic presentations of products or corporations benefit simplicity and allows the interpreter to adequately decorate the core meaning with a locally well understood business jargon, tone and manner that fit local understanding. The same applies at least very much here in Japan with conceptual stances. In business at least, the less conceptual bones to munch on, the better.

Is the interpreter entitled to suggest the client to control her speech blooming? Yes, granted the interpreter stresses with enough authority that the scheme is to get the message through, and that business flowers are the equivalent of literary citations and good jokes. They only put useless stress on the interpreter and do not benefit the speaker. Without authority when suggesting to keep things simple,  the interpreter takes the risk to be perceived as inadequate to the job. Whereas the client has authority on her corporation and product's content and context, the interpreter must suggest that authority in the knowledge of what works and what doesn't is her own turf. I don't suggest that this should apply to any situations. There are official, formal situations where the speaker will be expected to show off culture and expose her wits with "bon mots". But the meeting room is not an adequate place to do so, all the more that flowery and witty speeches - usually coming with cultural hints and bits - may actually be totally foreign to the listener's cultural context.

Keeping things simple does not mean talking to children but sticking to the fact. Being factual, rather than theoretical is a requisite, at least in Japan's business settings.