The filioque is not heretical, and makes sense in a Latin context. It is most definitely heretical to impose filioque on the Greek version of the Creed because doing so renders the Son acting in the Father’s sole spiration of the Holy Spirit - a detail confessed equally as True by Latins, Greeks, Syriacs, etc (In other words, “two gods”). Filioque in Latin means proceeds from (e.g.through), in Greek it means proceeds in origin “from the Father and Son”, a detail denied by every Apostolic Church.
As you see here, imposing Latin phrases and terminology on another Patristic Tradition can be detrimental, to the point of heresy.
It also makes sense in a Greek context. We all know the information you posted above. The creed is not the totality of the Greek tradition. As we know the Greek fathers have numerous works teaching the filioque explicitly. The filioque is compatible with the Greek tradition in so far as the correct words are used.
The Greeks are concerned about the word in the creed “ekporeusis” (εκπορεύομαι), which pertains to an ultimate origin in Greek theology. Even in the Latin Church and theology the Father is the ultimate source of the Holy Spirit. However the filioque does not speak rigidly. It does not concern the beginning of the procession (ultimate origin) but the whole procession. That is, He proceeds from the father by way of the son. This is because the Latin word “processio” means “goes forward” and pertains not to ultimate origin as the word is not rigid in this sense. The complimentary Greek word for “processio” is “proienai” and not ekporeusis which was erroneously assumed as the Greek equivalent thus starting the whole controversy. The filioque is not foreign to the Greek tradition but is actually part of it!
Here are examples of the Greek speaking fathers teaching filioque :
St Cyril if Alexandria
“For, in that the Son is God, and from God according to nature (for He has had His birth from God the Father), the Spirit is both proper to Him and in Him and from Him, just as, to be sure, the same thing is understood to hold true in the case of God the Father Himself.”
St Athanasius of Alexandria
“David sings in the psalm [35:10], saying: 'For with You is the font of Life;'because jointly with the Father the Son is indeed the source of the Holy Spirit.”
"Everything the Spirit has, He has from the Word "
St Basil the Great
“He is second to the Son, having His being from Him and receiving from Him and announcing to us and being completely dependent on Him, pious tradition recounts”
St Epiphanios of Salamis
" For if he calls the one Who is from Him the Son, and the one Who is from both (παρ᾽ ἀμφοτέρων) the Holy Spirit"
“No one knows the Spirit except the Father and the Son, that is, the one from Whom He proceeds (εκπορεύομαι) and the one from Whom He receives, and that no one knows the Son and the Father except the Holy Spirit, He Who truly glorifies, Who teaches all things, Who is from the Father and the Son.”
St Gregory of Nyssa
“the Spirit both is said to be from the Father, and is further testified to be from the Son. For, it says, “if any man have not the Spirit of Christ, he is none of His” [Rom 8:9]. Therefore the Spirit, Who is from God, is also the Spirit of Christ; but the Son, Who is from God, neither is nor is said to be “of the Spirit,” nor does this relative order become reversed”