Nepal considering "STVS" proportional representation voting system

[Warren D Smith]

https://thehimalayantimes.com/nepal/system-ensures-proportional-representation/

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Warren D. Smith
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[Brian Langstraat]

A Single Transferable Voting System (STVS) could work well for Nepal's provincial elections of members to the National Assembly.

About half of this article focuses on how to select members from certain underrepresented groups.

As per the constitutional provision, each province will elect eight members to the National Assembly, including three women, one Dalit candidate and one differently-abled candidate or candidate from minority community.

The two solutions mentioned seem unnecessarily complicated with multiple separate votes:

[Uprety] said the EC could have four separate ballot papers or one ballot paper with four clusters- three women- three candidates under open cluster, one Dalit candidate and one differently abled candidate or candidate from minority community.

 or

[Pariyar proposed to] elect six members on the basis of STVS and two members — one Dalit and one differently-abled or a member from minority community — on the basis of first-past-the-post electoral system.

Simply, they could just have a single vote on one ballot using STVS.

In each round of counting, the candidate(s) that reaches the winning threshold in each category are the winners.

In cases of too many winners in a specific category, the candidates with the most first-round votes is the winner.

When all of the winners in a category are filled, the votes for "losing" candidates that do not qualify for a remaining unfilled category are transferred to candidates that do qualify for a remaining unfilled category.

In cases of a category that has x unfilled seats that cannot be filled by candidates that reach the winning threshold, the x remaining candidates after elimination rounds are the winners.

For example:

First round: 4 non-underrepresented candidates pass the winning threshold, so the votes for the 1 non-underrepresented candidate with the least votes would be transferred to underrepresented candidates.

Second round: With transferred votes, 2 female candidates and 1 Dalit candidate pass the winning threshold, so the votes for the "abled" male Dalit candidates would be transferred to female and differently abled candidates.

Third round: With transferred votes, 1 differently abled candidate passes the winning threshold and 2 female candidates remain that do not pass the winning threshold.

Fourth Round: The female candidate with the least votes is eliminated, so the remaining female candidate is the final winner.

Are there any drawbacks to this STVS method?

Can Reweighted Range Voting (RRV) or other Proportional Representation (PR) methods handle mandatory representation from certain groups?