The sound changes look plausible, but I’m not sure how the DPD put paṇḍu and paṇḍaka in the same word family. The PED does it differently; it has the Latin cognates palleo ‘I grow pale’ and pello ‘I hit/ expell’, arguably different meanings with different roots. I don’t have access to the PED source for pello.
According to the Indo-European Language Association – http://dnghu.org/ version of Pokorny’s An Etymological Dictionary of the Proto-Indo-European Language there are a couple of possible roots in play:
pel-6
English meaning: grey; pale
Deutsche Übersetzung: in Ausdrũcken for unscharfe Farben as “grau, fahl”, also ‘scheckig”
Material: O.Ind. palitá-, fem. páliknī (from *-tnī) “altersgrau, greis” (: πελιτνός), paruṣá-
“fleckig” = Av. pouruša-, paouruša- “gray, old”; pers. pūr “gray” (*parya-);
Arm. alik” “die (weißen) waves, billows; white Bart, weißes hair” (*pl̥ii̯o-);
Gk. πελιτνός “gray” (for *πελιτός = O.Ind. palitá-ḥ after dem Fem. *πελιτνια = O.Ind.
paliknī); Ion. πελιδνός out of it after μακεδνός etc. reshaped; πελιός (*peli-u̯o-) “farblos,
pallid, grauschwarz, bluish black” (here the PN Πέλοψ), πελλός ds. (*πελι̯ός? *πελνός?),
πολιός “gray, greis” (*poli-u̯o-), πιλνόν φαιόν Κύπριοι Hes.; πέλεια, πελειάς “wild dove”
(after the Farbe benannt, compare πέλειαι, πελειάδες, eig. die grauköpfigen, old, as
Bezeichnung the Priesterinnen in Dodona as well as πέλειος “age” Hes.; also Lat.
palumbēs, O.Pruss. poalis “dove”), πελᾱργός ‘swan” (“the schwarzweiße”); from *πελαF(ο)-
- αργός; Maced. πέλλης “τεφρώδης” Hes.; probably here also πηλός, Dor. πᾱλός (*παλσός)
“ loam, clay, slime, mud, ordure, morass”;
Lat. palleō, -ēre “pale, wan sein”, pallor “paleness”, pallidus “pale, wan” (at first from
*palu̯os, older *polu̯os = Gmc. falwa-, Lith. paɫvas, O.C.S. plavъ); pullus ‘schwarzgrau” (ul
from l̥ infolge of anlaut. p-; forms -no-); palumbēs or -is “wood-, Ringeltaube” (*pelon-bho-?
rather parallel formation to columbus, -a, see above S. 547);
Note:
Alb. (*palumb) pëllumb “dove” shares the same root with Lat. palumbes -is, m. and f. “a
wood pigeon, ring dove”. It is not a Lat. loanword otherwise the ending -es, -is would have
been solidified in Alb. like Lat. radius > Alb. rreze “ray”; actually Lat. could have borrowed
this cognate from Illyr. since the shift m > mb is a typical Alb. not Lat. phonetic mutatIon. Alb. plak “ graybeard, Ältester”;
M.Ir. liath, Welsh (etc.) llwyd “gray” (from *pleito-, compare O.Ind. palitá-, Gk. πελιτνός);
Gmc. *falwa- in O.Ice. fǫlr, O.E. fealo, O.S. falu, O.H.G. falo, falawēr ‘sallow, paled, falb”
(in addition as “graue ash” O.Ice. fǫlski m., O.H.G. falawiska “ash, Aschenstäubchen”);
*falha- (: Lith. pálšas) in alemO.N.-rheinfränk. falch “falb, esp. from hellbraunem Vieh”;
*fela- or *felwa- in Westfäl. fęl “falb”, fęle “fahles roe deer, fahles horse”; with dem Gmc. k-
forms as in other bird name here presumably O.H.G. (etc.) falco “falcon” (late Lat. falco
from dem Gmc.);
Lith. pal̃vas “blaßgelb” (= Gmc. *falwa, Lat. palli-dus) = O.Bulg. plavъ “white”, Serb. plûv
“blond, blue”; Lith. pelẽ “ mouse “, Ltv. pele ds., O.Pruss. peles pl. “ mouse (= Armmuskel)”,
O.Pruss. pele “consecration”; as derivative from pelẽ “ mouse “ also Lith. pelékas, Ltv.
pelēks “mausfarbig, sallow, paled, gray”; Lith. peléda, Ltv. pęlêda “owl “ (“Mäusefresserin”);
from a *pelẽ “ mildew “ derives Lith.pele-́ ju, -ti “ mildew “, pelésiai pl. “ mildew “ and in ablaut
plék-stu, -ti “ mildew, modern”; in ablaut Lith. pìlkas “gray”, pélkė “Moorbruch”, also pálšas,
Ltv. pàlss ‘sallow, paled” (*polk̂os) as well as O.Pruss. poalis “dove” (*pōlis); Slav. *plěsnь
in R.C.S. plěsnь, O.Cz. pléseň “ mildew “ and Church Slavic peles “pullus”, Russ. pelësyj
“mottled, speckled, *tabby, varicolored”; das forms IE -so- or -k̂o-.
References: WP. II 53 f., WH. II 239 f., 242, 386, Trautmann 205, 212;
See also: see above S. 799 C (pel-1).
Page(s): 804-805
badi̯os
English meaning: gold, brown
Deutsche Übersetzung: “gelb, braun”
Note: (only Lat. and Ir.; maybe from one, at most not IE, language of ancient Europe?).
Material: Lat. badius “ brown, chestnutcolored, bay “; O.Ir. buide “gold, yellow” (compare to
Lautl. O.Ir. mag “field”, gen. muige; Gaul. Bodiocasses because of о rather for boduo-,
about which under *bhaut- “ hit “). Gk. βάδιος, βάδεος derives from Lat.
References: WP. II 105, WH. I 92.
I can’t find a root close to pello. The second entry giving the Old Irish for ‘yellow’ shows the change in Sanskrit might be from b > p and from Latin to Greek; intriguingly, it has a link between ‘yellow’ and ‘hit’, but the entry for *bhaut- “ hit" is missing from my dictionary. This will take a lot more detective work, but I have reached my limit.
Also, I’m not confident that the PED is on the right track with either cognate, including palleo (in pel-6), for which Pokorny only gives palita and paliknī for Sanskrit descendants ; I wonder if there is a Dravidian/ Munda origin to these words. Certainly Levman Pāli and Buddhism p55 gives paṇḍu as derived from Santali. If that is the right approach, we would need to suppose there is some unusual transmission route for these words into Indo-European languages; in which case it’s highly doubtful that anything can be proven.