Goddard and Langi are both good prospects, but neither will be ready for a starting gig (or any further advanced than Botha and Amone) next year. I'm not saying the tahs need a world class tight head, just that they need a reliable super rugby standard one, and of all the open positions they have it's the one that will be hardest to find, so they really need to be proactive in the market. If they don't get that their scrum will look like an achilles heel for at least a season, and management of Bell's minutes will probably get more difficult. I guess they might look at shifting Lambert across, but that always takes time and I'm not sure it'll help them much next year.
I do think they probably also need to find at least one more experienced back to have around the group, whether or not they are actually in the regular 15/23, though a starting centre would probably be perfect, particularly from a defensive perspective. That is predicated on the idea that they'll lose Foketi though, which I think is pretty likely but yet to actually play out. The rest of the open/potentially open positions can probably filled well locally (assuming good retention), though there might be some question marks at hooker depending on how Porecki holds up.