It's very hard to compare the situations.
I don't contend they are equivalent, but they are parallel - enough to show (IMO) that an elector being a foreign king was not intrinsically a big problem.
In all three cases, the holder had the electorate first and the kingdom second.
Dynastically this would be the same. The House of Wittelsbach has held the County Palatine since 1214, but inherits England and Scotland only at the death of Elizabeth (not till 1662, OTL). Henry Frederick would inherit the County and Electorate when his father Frederick V dies (1632 OTL), though not actual possession.
None of those electors were technically still under imperial ban when they became king of another country.
The question will be whether the ban would be sustained against Frederick V because his wife is Queen of England and Scotland, and against Henry Frederick because he is heir to England and Scotland. If as suggested, England joins the Protestant side in the TYW, that would put more pressure on Ferdinand.
When Frederick V dies is key. OTL he went on campaign with Gustavus in 1632, left for home after Gustavus turned him down, and caught some kind of fatal infection on the road. All that will be butterflied, as will Gustavus' death at Lutzen. It should be noted Frederick was seriously injured in the OTL ferry accident that killed Henry Frederick, so that's another butterfly. Also, OTL Gustavus wouldn't support Frederick without explicit English backing or some onerous conditions. ITTL, Frederick will have that backing.
ISTM quite plausible that with Elizabeth as Queen, Frederick has explicit English support, Gustavus signs on, they both survive longer, and Ferdinand has to restore Frederick as a peace condition around 1635.
It's possible that Frederick dug himself in too deep to be restored, even with this additional aid. However, the domain and titles could be "restored" to Henry Frederick.