XeLaTeX - Issue with Devanagari header

I'm currently working on a project wherein I'm using RomDev mapping technique to print Devanagari characters using Roman transliteration through XeLaTeX.

The Minimum Working Example is as follows:

\usepackage{polyglossia}%%%%%%%%%%%%%%%%%%%%%%%\setmainfont{Lato}\newfontfamily\fc{Lohit Devanagari}[Mapping=RomDev,Script=Devanagari]\newfontfamily\fsh{Lohit Devanagari}[Script=Devanagari]%%%%%%%%%%%%%%%%%%%%%%%\begin{document}\chapter{\fc{arjuna viṣāda yoga} -- Arjuna viṣāda yoga}\begin{center}\textbf{\textbar{}\textbar{} 1.1 \textbar{}\textbar{}}\fc{\textit{dhṛtarāṣṭra uvāca}dharmakṣetre kurukṣetre samavetā yuyutsavaḥ |māmakāḥ pāṇḍavāścaiva kimakurvata sañjaya}\end{center}\begin{center}\textit{dhṛtarāṣṭra uvāca}dharma-kṣetre kuru-kṣetre samavetā yuyutsavaḥmāmakāḥ pāṇḍavāś caivakim akurvata sañjaya\end{center}\begin{center}\textbf{    \textbar{}\textbar{} 1.2 \textbar{}\textbar{}} \fc{\textit{sañjaya uvāca}    dṛṣṭvā tu pāṇḍavānīkaṃ  vyūḍhaṃ duryodhanastadā | \textbar{}ācāryamupasaṅgamya          rājā vacanamabravīt}\end{center}\begin{center}\textit{sañjaya uvāca}dṛṣṭvā tu pāṇḍavānīkaṁvyūḍhaṁ duryodhanas tadāācāryam upasaṅgamyarājā vacanam abravīt\end{center}\begin{center}\textbf{\textbar{}\textbar{} 1.3 \textbar{}\textbar{}}\\ \fc{paśyaitāṃ pāṇḍuputrāṇāmācārya mahatīṃ camūm vyūḍhāṃ drupadaputreṇa  tava śiṣyeṇa dhīmatā}\end{center}\begin{center}paśyaitāṁ pāṇḍu-putrāṇāmācārya mahatīṁ camūmvyūḍhāṁ drupada-putreṇatava śiṣyeṇa dhīmatā\end{center}\begin{center}\textbf{    \textbar{}\textbar{} 1.4 \textbar{}\textbar{}}\\ \fc{atra śūrā maheṣvāsā  bhīmārjunasamā yudhi    yuyudhāno virāṭaśca     drupadaś ca mahārathaḥ}\end{center}\begin{center}    atra śūrā maheṣvāsā    bhīmārjuna-samā yudhi    yuyudhāno virāṭaś ca    drupadaś ca mahā-rathaḥ\end{center}\begin{center}    \textbf{    \textbar{}\textbar{} 1.5 \textbar{}\textbar{}}    \\ \fc{dhṛṣṭaketuścekitānaḥ kāśirājaśca vīryavān     purujit kuntibhojaśca śaibyaśca narapuṅgavaḥ}\end{center}\begin{center}    dhṛṣṭaketuś cekitānaḥ    kāśirājaś ca vīryavān    purujit kuntibhojaś caśaibyaś ca nara-puṅgavaḥ\end{center}\begin{center}    \textbf{    \textbar{}\textbar{} 1.6 \textbar{}\textbar{}}    \\ \fc{yudhāmanyuśca vikrānta uttamaujāśca vīryavānsaubhadro draupadeyāśca sarva eva mahārathāḥ}\end{center}\begin{center}yudhāmanyuś ca vikrāntauttamaujāś ca vīryavānsaubhadro draupadeyāś ca sarva eva mahā-rathāḥ\end{center}\begin{center}\textbf{    \textbar{}\textbar{} 1.7 \textbar{}\textbar{}}\\ \fc{asmākaṃ tu viśiṣṭā ye tānnibodha dvijottama    nāyakā mama sainyasya   saṃjñārthaṃ tānbravīmi te}\\\end{center}\begin{center}asmākaṁ tu viśiṣṭā yetān nibodha dvijottamanāyakā mama sainyasyasaṁjñārthaṁ tān bravīmi te\end{center}\end{document}

I've shared a link with the screenshot of the exact issue. It shows how the header is jumbled up. Also one can see how we are able to generate both the Roman transliteration and the Devanagari script quite flawlessly.

My questions are:

1. Why are the Devanagari characters in the header getting messed up? How can it be rectified?
2. Can I make the header to not get formatted in Italics+CAPS?

Thanks in advance.