I am in a very similar situation, working for a mid-sized logistics (300 employees with small offices around the globe, 400-500M annual revenue), but with a completely different side, we do practically everything in-house with a very old software that does everything, (Multivalue D3).
My experience on your points:
>We're having to resort to a separate low-code platform to fill in the gaps. Our business operates in a specific niche and there are no other providers who cater specifically to our industry.
We also use low-code applications like Talend and TIBCO, to fill some gaps, the older folks that don't want to deal with our ERP prefer using them this way for example.
Have you tried taking a look to https://www.flexport.com/ or https://www.shipbob.com/? Afaik, these are 2 of the most overrall used in the logistics industry.
We are very slowly migrating our system in different departments to more modern solutions, but always keep in mind that as soon as you start migrating, you will need to keep both systems up for a long period of time while this happens, and that means money and workers.
>On the other hand, while our current solution seems like a straightforward CRUD app, I fear the devil is in the details. Will we get stuck at 80% completion? We do a lot of data exchange via EDIFACT, for instance, with various government institutions all over Europe. This feels like a quagmire in which development can quickly stall.
Europe is slowly moving outside of the EDIFACT standard fortunately and slowly implementing SOAP/XML based systems, you will have a problem here in an in-house solution because Europe systems are usually convoluted and hard to implement from different countries, from a business-side pov exclusively. ( I can tell you from first hand experience ), so indeed, a big problem will arise here. If you also do customs clearance, this will get even harder, as laws vary from place to place in small and big details.
>Strategies for attracting and retaining tech talent in a non-tech industry Experiences transitioning...
Finding them is hard, but keeping them is harder, any other logistics company that sees a trained IT specialist with deep business knowledge will try to poach it with a higher wage inmediatly, I had tons of offers from close companies because of my customs knowledge. Pay them well and keep them happy. There is no strategy here, devs move for money like everywhere else, some end up in banks or insurance after some consultancy job with business experience and stick there, you will have to risk training them in house or poaching them from elsewhere.
For an industry as complex and in my opinion, enterprise customizable company, I highly recommend you to try an in-house solution, users sometimes don't need a lot to do their work and the most important thing in logistics is being able to do it quickly and efficiently.
What I can tell you absolutely that it doesn't work is trying to migrate from a big swoop, I saw companies close to us do it and it just didn't work out, their processes slowed down a lot and clients started fleeing to other forwarders because of the time they took to process any shipment. Move slowly in your smallest department ( reefer, customs, import or export, invocing, anything that in your company isn't as importante) and move efficiently, make their work as fast as possible, then grab that feedback and start moving other departments.