[Goose]

Seems to me dumping a bunch of equipment at once in a country that is not familiar with operating or mantaining it all at once probably would not lead to good use of that equipment.

You are undoubtedly correct there. Even storing it in Ukraine increases the probability Russia can find it and destroy it before it gets used. It is also true that announcing our intentions in advance may make people like me feel better but doesn't actually help until it becomes reality.

The people who needed to learn the M777 likely overlap significantly with those who need to learn HIMARS.

I don't think this is the case, although there are lots of variables. If linguistic ability is the issue, it might reduce the possible choices. By now, I would expect HIMARS and MLRS manuals are available in Ukrainian, as we have had months to do that. I would also expect instructors from both US and Polish sources that speak Ukrainian are available, but that could be an issue.
For the M777 I would expect the Ukrainians would have chosen trainers/gunners/13Bs who are very familiar with the existing  Ukrainian legacy 152 mm guns. This is especially true given the abbreviated time available for training them. OTOH, for the HIMARS I would expect trainers/13Ms who are Grad operators/trainers out of work because they are short of missiles. Totally different skill sets, and in all armies I am familiar with totally different personnel groups. The HIMARS is also simpler to learn than being a cannon crew member. In the US army 13M advanced training is 4 weeks while 13B is 7 weeks. The Ukrainians would also undoubtedly prefer these groups be disjoint simply to increase their own training capability.

If you want to call it a mistake, then the mistake was not supplying this stuff years ago.

It is probably correct that the US should have done more to help Ukraine after 2014. There are lots of reasons that didn't happen, but certainly in hindsight more should have been done. However, I still believe that the US should have moved to start the HIMARS transfer back in March. It was clear at the time Ukraine lacked a significant deep strike capability. Being further down that road would possibly have stopped the problem in the Donbas from escalating  as far as it has. I don't see what the two months delay accomplished.

[Goose]

Seems to me dumping a bunch of equipment at once in a country that is not familiar with operating or mantaining it all at once probably would not lead to good use of that equipment.

You are undoubtedly correct there. Even storing it in Ukraine increases the probability Russia can find it and destroy it before it gets used. It is also true that announcing our intentions in advance may make people like me feel better but doesn't actually help until it becomes reality.

The people who needed to learn the M777 likely overlap significantly with those who need to learn HIMARS.

I don't think this is the case, although there are lots of variables. If linguistic ability is the issue, it might reduce the possible choices. By now, I would expect HIMARS and MLRS manuals are available in Ukrainian, as we have had months to do that. I would also expect instructors from both US and Polish sources that speak Ukrainian are available, but that could be an issue.
For the M777 I would expect the Ukrainians would have chosen trainers/gunners/13Bs who are very familiar with the existing  Ukrainian legacy 152 mm guns. This is especially true given the abbreviated time available for training them. OTOH, for the HIMARS I would expect trainers/13Ms who are Grad operators/trainers out of work because they are short of missiles. Totally different skill sets, and in all armies I am familiar with totally different personnel groups. The HIMARS is also simpler to learn than being a cannon crew member. In the US army 13M advanced training is 4 weeks while 13B is 7 weeks. The Ukrainians would also undoubtedly prefer these groups be disjoint simply to increase their own training capability.

If you want to call it a mistake, then the mistake was not supplying this stuff years ago.

It is probably correct that the US should have done more to help Ukraine after 2014. There are lots of reasons that didn't happen, but certainly in hindsight more should have been done. However, I still believe that the US should have moved to start the HIMARS transfer back in March. It was clear at the time Ukraine lacked a significant deep strike capability. Being further down that road would possibly have stopped the problem in the Donbas from escalating  as far as it has. I don't see what the two months delay accomplished.