Does lead carry the negative charge in plumbane? It says in Wikipedia that lead tetrahydride or hydrogen plumbide or plumbane ($\ce{PbH4}$) is supposed to have lead in its -4 state and the hydrogen is in its +1 state because supposedly lead has a higher electronegativity than hydrogen. Is this possible to be synthesized and actually be stable for long enough to at least view it?
$\ce{Pb^{4+}}$ is very unstable due to the inert pair effect, wherein for p-block elements lower oxidation state becomes stabler as we move down the group. Also, the main factor is the electronegativity of lead being more than hydrogen, which you stated in your question (although they are very close). Hence the oxidation states would not be flipped.