A quarter of a century old 73 key synth action keyboard might not be ideal but it's a starting place that's a little better than many people's 25-49 key synth action and even semi weighted keyboards, if it is in fine condition.
I understand that the Roland A33 is synth action not semi weighted or hammer action.
I won't pretend to be a serious pianist, but I do know that ideally you want to be using graded hammer action (graded meaning most notably heavier action in the bass range), if you want to be even slightly serious about learning piano technique.
You would have adjust the velocity curve to best suit your keyboard, however only so much can be achieved. You cannot compensate for the wrong type of action.
I don't even think it's just about translatable technique (to acoustic piano). When you're using semi weighted or synth action it is too easy to accidentally trigger the wrong velocity, messing up the expressivity of your performance. Basically it's too sensitive when you don't want it to be.
With most synth action keyboards it is extremely easy to hit maximum velocity, or they limit you below maximum velocity.
Synth action means a light spring behind each key.
In contrast hammer action means each key is weighted, and it is this weight that returns the key to it's normal position.
Basically with synth action it is easy to trigger the sounds. It's not like the sensation of using a percussive instrument.
The middle ground is a heavier spring design called semi-weighted. Typically chunky keys more akin to a piano key with some weights and a stiffer (but slower) action. It's not really suitable for piano either.
For piano you only really want hammer-action, given the choice.